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  • Question 1 - Which of the following best describes the process of opsonisation: ...

    Correct

    • Which of the following best describes the process of opsonisation:

      Your Answer: The coating of foreign particles with molecules which allow easier recognition of that cell by phagocytes

      Explanation:

      An opsonin is any molecule that enhances phagocytosis by marking an antigen for an immune response, for example, immunoglobulin or complement. Opsonisation is the molecular mechanism whereby molecules, microbes, or apoptotic cells are chemically modified to have a stronger attraction to the cell surface receptors on phagocytes and natural killer cells. With the antigen coated in opsonins, binding to immune cells is greatly enhanced. Opsonisation also mediates phagocytosis via signal cascades from cell surface receptors.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      10.5
      Seconds
  • Question 2 - Which of the following statements is correct with regards to natural killer cells?...

    Correct

    • Which of the following statements is correct with regards to natural killer cells?

      Your Answer: They are part of the innate immune system.

      Explanation:

      Natural Killer (NK) Cells are lymphocytes in the same family as T and B cells, which come from a common progenitor. They are cytotoxic CD8 positive cells that do not have the T-cell receptor. They are very big cells with cytoplasmic granules and are designed to kill target cells with a low level of expression of HLA class I molecules. Examples include during a viral infection or on a malignant cell. NK cells display several receptors for HLA molecules on their surface, and when HLA is expressed on the target cell, these deliver an inhibitory signal into the NK cell. Absent HLA molecules on the target cell cause this inhibitory signal to get lost and as a result, the NK cell can then kill its target. Also, NK cells display antibody-dependent cell-mediated cytotoxicity, where antibody binds to antigen on the surface of the target cell. The NK cells then bind to the Fc portion of the bound antibody and kill the target cell.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      8
      Seconds
  • Question 3 - Eosinophils comprise what percentage of circulating white cells: ...

    Correct

    • Eosinophils comprise what percentage of circulating white cells:

      Your Answer: 1 - 3%

      Explanation:

      Eosinophils comprise 1 – 3% of circulating white cells. Eosinophils are similar to neutrophils, except that the cytoplasmic granules are coarser and more deeply red staining, and there are rarely more than three nuclear lobes. They are less motile, but longer lived. They enter inflammatory exudates and have a special role in allergic responses, defence against parasites and removal of fibrin formed during inflammation. Thus they play a role in local immunity and tissue repair.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      4.8
      Seconds
  • Question 4 - Mast cells play a significant part in which of the following? ...

    Correct

    • Mast cells play a significant part in which of the following?

      Your Answer: Allergic disease

      Explanation:

      Mast cells play a central role in the response to allergen challenges. The activation of mast cells results in both an early and a delayed phase of inflammation. Mast cells have been implicated in both physiologic and pathogenic processes. Mast cells are important in defence against some bacteria and viruses and contribute to defence against parasites. They are key effector cells in both innate and acquired immunity and are capable of inducing and amplifying both types of responses. Specifically, mast cells are capable of detecting microbial products through surface pattern recognition receptors, and they are involved in the recruitment of other leukocytes, containment of bacterial infections, and tissue repair.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      5.9
      Seconds
  • Question 5 - Which of the following blood groups is the least common in the UK:...

    Correct

    • Which of the following blood groups is the least common in the UK:

      Your Answer: AB

      Explanation:

      Blood group O is the most common in the UK (46 %), followed by group A (42 %), group B (9 %) and finally group AB (3 %).Blood group O has no antigens, but both anti-A and anti-B antibodies and thus is the universal donor. Blood group AB has both A and B antigens but no antibodies and thus is the universal recipient.Blood group A has A antigens and anti-B antibodies and blood group B has B antigens and anti-A antibodies.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      3.4
      Seconds
  • Question 6 - The following are all examples of type II hypersensitivity EXCEPT for: ...

    Incorrect

    • The following are all examples of type II hypersensitivity EXCEPT for:

      Your Answer: Haemolytic disease of the newborn

      Correct Answer: Post-streptococcal glomerulonephritis

      Explanation:

      Examples of type II reactions include: Incompatible blood transfusionsHaemolytic disease of the newbornAutoimmune haemolytic anaemiasGoodpasture’s syndromeRheumatic heart diseaseBullous pemphigoid

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      20.4
      Seconds
  • Question 7 - C3 deficiency leads to particular susceptibility of infection with which of the following:...

    Correct

    • C3 deficiency leads to particular susceptibility of infection with which of the following:

      Your Answer: Encapsulated bacteria

      Explanation:

      Macrophages and neutrophils have C3b receptors and they phagocytose C3b-coated cells. C3 deficiency thus leads to increased susceptibility of infection with encapsulated organisms (e.g. S. pneumoniae, H. influenzae).The early stages of the complement cascade leading to coating of the cells with C3b can occur by two different pathways:The classical pathway usually activated by IgG or IgM coating of cellsThe alternative pathway which is more rapid and activated by IgA, endotoxin and other factors

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      5.9
      Seconds
  • Question 8 - A 43 year old lady suffering with idiopathic thrombocytopenic purpura has a splenectomy....

    Correct

    • A 43 year old lady suffering with idiopathic thrombocytopenic purpura has a splenectomy. She is advised to get the Pneumococcal vaccine booster every 5 - 10 years as Streptococcus pneumoniae has which of the following properties that make her prone to infection to this organism?

      Your Answer: It is encapsulated

      Explanation:

      There is a lifelong susceptibility to increased risk of infection from a variety of organisms in patients with hyposplenism, especially in children under 5 years and those with sickle cell anaemia. Patients are most susceptible is to the encapsulated bacteria Streptococcus pneumoniae, Haemophilus influenzae type B and Neisseria meningitidis. Streptococcus pneumoniae is particular concerning as it can cause rapid and fulminant disease, which can be fatal. Malaria and animal bites that become infected also tend to be more severe.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      14.5
      Seconds
  • Question 9 - Which of the following does NOT typically cause a neutrophil leucocytosis: ...

    Incorrect

    • Which of the following does NOT typically cause a neutrophil leucocytosis:

      Your Answer: Corticosteroid therapy

      Correct Answer: Glandular fever

      Explanation:

      Causes of neutrophil leucocytosis:Bacterial infectionInflammation and tissue necrosis (e.g. cardiac infarct, trauma, vasculitis, myositis)Metabolic disorders (e.g. uraemia, acidosis, eclampsia, gout)PregnancyAcute haemorrhage or haemolysisNeoplasms of all typesDrugs (e.g. corticosteroid therapy, lithium, tetracyclines)AspleniaMyeloproliferative disorders (e.g. CML, essential thrombocythaemia, polycythaemia vera, myelofibrosis)Rare inherited disorders

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      20.8
      Seconds
  • Question 10 - Which of these immunoglobulin molecules can cross the placenta? ...

    Correct

    • Which of these immunoglobulin molecules can cross the placenta?

      Your Answer: IgG

      Explanation:

      An important mechanism that provides protection to the foetus is placental transfer of maternal IgG antibodies while his/her humoral response is inefficient. The only antibody class that significantly crosses the human placenta is IgG.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      4.1
      Seconds
  • Question 11 - Which of the following ABO blood groups is the universal recipient: ...

    Incorrect

    • Which of the following ABO blood groups is the universal recipient:

      Your Answer: O

      Correct Answer: AB

      Explanation:

      Blood group AB has both A and B antigens but no antibodies and thus is the universal recipient.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      8.3
      Seconds
  • Question 12 - The following are all examples of type IV hypersensitivity EXCEPT for: ...

    Incorrect

    • The following are all examples of type IV hypersensitivity EXCEPT for:

      Your Answer: Sarcoidosis

      Correct Answer: Extrinsic allergic alveolitis

      Explanation:

      Examples of type IV reactions includes:Contact dermatitisHashimoto’s thyroiditisPrimary biliary cholangitisTuberculin skin test (Mantoux test)Chronic transplant rejectionGranulomatous inflammation (e.g. sarcoidosis, Crohn’s disease)

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      5.9
      Seconds
  • Question 13 - The most important Complement protein for antigen opsonization is: ...

    Incorrect

    • The most important Complement protein for antigen opsonization is:

      Your Answer:

      Correct Answer: C3b

      Explanation:

      Phagocytosis is largely responsible for depletion of cells coated with antibodies. Cells opsonized by IgG antibodies are recognized by phagocyte Fc receptors, which are specific for the Fc portions of some IgG subclasses. In addition, when IgM or IgG antibodies are deposited on the surfaces of cells, they may activate the complement system by the classical pathway. Complement activation generates by-products, mainly C3b and C4b, which are deposited on the surfaces of the cells and recognized by phagocytes that express receptors for these proteins. The net result is phagocytosis of the opsonized cells and their destruction.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 14 - What proportion of peripheral blood leukocytes are monocytes? ...

    Incorrect

    • What proportion of peripheral blood leukocytes are monocytes?

      Your Answer:

      Correct Answer: 5 - 10%

      Explanation:

      Monocytes account for around 5 to 10% of peripheral white cells. Monocytes in peripheral blood are generally bigger than other leukocytes and feature a large central oval or indented nucleus with clumped chromatin. The abundant cytoplasm staining blue and containing numerous fine vacuoles gives the appearance of ground glass. Cytoplasmic granules are another type of granule. Monocytes evolve from the granulocyte-macrophage progenitor to become monoblasts, promonocytes, monocytes, and tissue macrophages (in increasing order of maturity). Monocytes only stay in the bone marrow for a short time before exiting to circulate in the bloodstream for 20-40 hours before becoming macrophages.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 15 - The following are all examples of type III hypersensitivity EXCEPT for: ...

    Incorrect

    • The following are all examples of type III hypersensitivity EXCEPT for:

      Your Answer:

      Correct Answer: Goodpasture's syndrome

      Explanation:

      Examples of type III reactions include:Extrinsic allergic alveolitisSystemic lupus erythematosus (SLE)Post-streptococcal glomerulonephritisReactive arthritisRheumatoid arthritis

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 16 - Regarding basophils, which of the following statements is INCORRECT: ...

    Incorrect

    • Regarding basophils, which of the following statements is INCORRECT:

      Your Answer:

      Correct Answer: They are the second most common type of granulocyte.

      Explanation:

      Basophils are only occasionally seen in normal peripheral blood comprising < 1% of circulating white cells. However, they are the largest type of granulocyte. They have many dark cytoplasmic granules which overlie the nucleus and contain heparin and histamine. They have immunoglobulin E (IgE) attachment sites and their degranulation is associated with histamine release. Basophils are very similar in both appearance and function to mast cells.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 17 - You are giving a presentation on the immune system as part of your...

    Incorrect

    • You are giving a presentation on the immune system as part of your peer-to-peer teaching sessions. Yu are currently discussing phagocytes. Macrophages are derived from which of the following cells:

      Your Answer:

      Correct Answer: Monocytes

      Explanation:

      Monocytes spend only a short time in the marrow and, after circulating for 20-40 hours, leave the blood to enter the tissues where they become macrophages. Macrophages form the reticuloendothelial system in the liver, spleen and lymph nodes. The lifespan of macrophages may be as long as several months or even years. In tissues the macrophages become self-replicating without replenishment from the blood. They assume specific functions in different tissues e.g. dendritic cells which are involved in antigen presentation to T-cells. Macrophages may be activated by cytokines such as IFN-gamma, contact with complement or direct contact with the target cell through leucocyte adhesion molecules.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 18 - Approximately what proportion of lymphocytes are B-cells: ...

    Incorrect

    • Approximately what proportion of lymphocytes are B-cells:

      Your Answer:

      Correct Answer: 0.2

      Explanation:

      B-cells (20% of lymphocytes) mature in the bone marrow and circulate in the peripheral blood until they undergo recognition of antigen. B-cell immunoglobulin molecules synthesised in the cell are exported and bound to the surface membrane to become the B-cell receptor (BCR) which can recognise and bind to a specific antigen (either free or presented by APCs). The BCR is also important for antigen internalisation, processing and presentation to T helper cells. Most antibody responses require help from antigen-specific T helper cells (although some antigens such as polysaccharide can lead to T-cell independent B-cell antibody production). When the B-cell is activated, the receptor itself is secreted as free soluble immunoglobulin and the B-cell matures into a memory B-cell or a plasma cell (a B-cell in its high-rate immunoglobulin secreting state). Plasma cells are non-motile and are found predominantly in the bone marrow or spleen. Most plasma cells are short-lived (1 – 2 weeks) but some may survive much longer. A proportion of B-cells persist as memory cells, whose increased number and rapid response underlies the augmented secondary response of the adaptive immune system.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 19 - Which of the following blood groups is the universal donor: ...

    Incorrect

    • Which of the following blood groups is the universal donor:

      Your Answer:

      Correct Answer: O

      Explanation:

      Blood group O has no antigens, but both anti-A and anti-B antibodies and thus is the universal donor.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 20 - Which of the following immunoglobulins is most important for mast cell degranulation: ...

    Incorrect

    • Which of the following immunoglobulins is most important for mast cell degranulation:

      Your Answer:

      Correct Answer: IgE

      Explanation:

      IgA is the major Ig in secretions, particularly from the gastrointestinal tract (but also in saliva, tears, sweat and breast milk).IgE is important for mast cell degranulation in allergic and antiparasitic response. In the allergic response, the plasma cell produces IgE-antibodies, which, like antibodies of other immunoglobulin isotypes, are capable of binding a specific allergen via its Fab portion.IgG is the most abundant in plasma (comprising 80% of normal serum immunoglobulin) and the main circulatory Ig for the secondary immune response.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 21 - Which of the following is NOT a function of antibodies: ...

    Incorrect

    • Which of the following is NOT a function of antibodies:

      Your Answer:

      Correct Answer: Act as antigen receptors on T lymphocytes

      Explanation:

      Antibodies: Neutralise toxins and prevent attachment of pathogensTarget, opsonise or agglutinate (clump together) antigens for phagocytosisActivate the complement cascade (leading to lysis or opsonisation of the pathogen)Act as antigen receptors on B lymphocytesActivate antibody-dependent cell-mediated cytotoxicity by natural killer (NK) cells or T cytotoxic cellsProvide mucosal immunity (IgA-mediated)Stimulate degranulation of mast cells (IgE and IgG mediated)Provide passive immunity to the newborn (through transplacental passage of IgG and secretion of IgA in breast milk)

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 22 - Which of the following laboratory findings are suggestive of functional hyposplenism: ...

    Incorrect

    • Which of the following laboratory findings are suggestive of functional hyposplenism:

      Your Answer:

      Correct Answer: Howell-Jolly bodies

      Explanation:

      Functional hyposplenism is characterised by the blood film findings of Howell-Jolly bodies or siderotic granules on iron staining. The most frequent cause is surgical removal of the spleen e.g. after traumatic rupture, but hyposplenism can also occur in sickle cell anaemia, gluten-induced enteropathy, amyloidosis and other conditions.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 23 - Which of the following immunoglobulin molecules is the most abundant in secretions (such...

    Incorrect

    • Which of the following immunoglobulin molecules is the most abundant in secretions (such as saliva and breast milk):

      Your Answer:

      Correct Answer: IgA

      Explanation:

      IgA is the predominant antibody class in secretions and tremendous quantities are secreted into various body spaces and onto mucosal surfaces (the gut lumen, the pharynx and sinuses, the larger airways, although not the alveoli). Because of its size, the majority of IgM is found in the circulation.Along with IgM, IgD is predominant among the surface receptors of mature B cells, where it plays a key role in B cells activation.IgE has the lowest concentration in normal human serum. It plays a prominent role in immune responses to helminth parasites, and in allergic reactions.IgG is the most abundant immunoglobulin and constitutes 75 percent of serum immunoglobulin in an adult human

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 24 - In all of the following conditions, lymphocytosis typically occurs except for: ...

    Incorrect

    • In all of the following conditions, lymphocytosis typically occurs except for:

      Your Answer:

      Correct Answer: Corticosteroid therapy

      Explanation:

      In infants and young children, lymphocytosis often occurs in response to infections that would normally produce a neutrophil reaction in adults.Lymphocytosis occurs in:1. Viral infections (e.g. infectious mononucleosis, HIV, rubella, mumps, viral hepatitis, cytomegalovirus, herpes simplex or zoster)2. Bacterial infections (e.g. pertussis, tuberculosis, toxoplasmosis, syphilis)3. Chronic lymphoid leukaemias4. Acute lymphoblastic leukaemias5. Non-Hodgkin lymphoma6. Thyrotoxicosis

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 25 - Which of the following is the most abundant peripheral blood leucocyte: ...

    Incorrect

    • Which of the following is the most abundant peripheral blood leucocyte:

      Your Answer:

      Correct Answer: Neutrophils

      Explanation:

      Neutrophils are the most abundant peripheral blood leucocyte, comprising about 50 – 70% of circulating white cells. Neutrophils have a characteristic dense nucleus consisting of between two and five lobes, and a pale cytoplasm with an irregular outline containing many fine pink-blue or grey-blue granules. The granules are divided into primary, which appear at the promyelocyte stage, and secondary, which appear at the myelocyte stage and predominate in the mature nucleus. Both types of granule are lysosomal in origin; the primary contains myeloperoxidase and other acid hydrolases; the secondary contains lactoferrin, lysozyme and other enzymes. The lifespan of neutrophils in the blood is only 6 – 10 hours. In response to tissue damage, cytokines and complement proteins, neutrophils migrate from the bloodstream to the site of insult within minutes, where they destroy pathogens by phagocytosis.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 26 - Regarding red blood cell group antigens and antibodies, which of the following statements...

    Incorrect

    • Regarding red blood cell group antigens and antibodies, which of the following statements is CORRECT:

      Your Answer:

      Correct Answer: Anti-D antibodies are usually IgG.

      Explanation:

      Approximately 400 red blood cell group antigens have been described. The ABO group antigens are unusual in that naturally occurring antibodies occur in the plasma of subjects who lack the corresponding antigen, even if they have not been exposed to that antigen previously. The most important of these natural antibodies are anti-A and anti-B, which are usually IgM. Anti-D antibodies don’t occur naturally, and are therefore immune antibodies that result from previous transfusions or pregnancy. Only IgG antibodies are capable of transplacental passage and the most important immune antibody is the Rh antibody, anti-D.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 27 - In which of the following would you NOT typically see a neutropaenia: ...

    Incorrect

    • In which of the following would you NOT typically see a neutropaenia:

      Your Answer:

      Correct Answer: Asplenism

      Explanation:

      Causes of neutropaenia:Drug-induced (e.g. chemotherapy, chloramphenicol, co-trimoxazole, phenytoin, carbamazepine, carbimazole, furosemide, chloroquine, clozapine, some DMARDs)Benign (racial or familial)CyclicalImmune (e.g. SLE, Felty’s syndrome, hypersensitivity and anaphylaxis)LeukaemiaInfections (e.g. HIV, hepatitis, fulminant bacterial infection)General PancytopaeniaHypersplenism, aplastic anaemia, malignant infiltration of bone marrow, megaloblastic anaemia, chemotherapy, myelodysplasia

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 28 - C5 - C9 deficiency increases susceptibility to infection with which of the following:...

    Incorrect

    • C5 - C9 deficiency increases susceptibility to infection with which of the following:

      Your Answer:

      Correct Answer: Neisseria spp.

      Explanation:

      If the complement sequence is completed, an active phospholipase (the membrane attack complex, MAC) is produced, which punches holes in the cell membrane and causes cell lysis. Because the MAC appears to be the sole means to destroy the Neisseria family of bacteria, C5 – C9 deficiency increases susceptibility to Neisseria infections.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 29 - Regarding T helper cells, which of the following statements is CORRECT: ...

    Incorrect

    • Regarding T helper cells, which of the following statements is CORRECT:

      Your Answer:

      Correct Answer: They form the vast majority (about 75%) of the total circulating T-cell population.

      Explanation:

      CD4+ T-cells (Helper T cells)Recognise antigen only in association with HLA class II molecules (found on antigen presenting cells (APCs) e.g. dendritic cells, B-cells; present exogenous antigens that have been phagocytosed/endocytosed into intracellular vesicles)Form most of the circulating T-cell population (about 75%)Secrete cytokines (e.g. IFN-gamma) which are required for recruitment and activation of other immune cells such as macrophages, T cytotoxic cells and NK cells and for the activation of and production of immunoglobulin from B-cells

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 30 - Which of the following is NOT typically associated with eosinophilia: ...

    Incorrect

    • Which of the following is NOT typically associated with eosinophilia:

      Your Answer:

      Correct Answer: Whooping cough

      Explanation:

      An eosinophil leucocytosis is defined as an increase in blood eosinophils above 0.4 x 109/L.It is most frequently due to:Allergic diseases (e.g. bronchial asthma, hay fever, atopic dermatitis, urticaria)Parasites (e.g. hookworm, ascariasis, tapeworm, schistosomiasis)Skin diseases (e.g. psoriasis, pemphigus, urticaria, angioedema)Drug sensitivity

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 31 - The following are all examples of type I hypersensitivity EXCEPT for: ...

    Incorrect

    • The following are all examples of type I hypersensitivity EXCEPT for:

      Your Answer:

      Correct Answer: Contact dermatitis

      Explanation:

      Examples of type I reactions include:Allergic rhinitisAllergic conjunctivitisAllergic asthmaSystemic anaphylaxisAngioedemaUrticariaPenicillin allergy

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 32 - A 22-year-old man arrives at the emergency department with a sore throat, low-grade...

    Incorrect

    • A 22-year-old man arrives at the emergency department with a sore throat, low-grade fever, and malaise. His partner has infectious mononucleosis, which was recently diagnosed. In this situation, which of the following cells is the most proliferative:

      Your Answer:

      Correct Answer: Lymphocytes

      Explanation:

      Histologic findings in EBV infectious mononucleosis: Oropharyngeal epithelium demonstrates an intense lymphoproliferative response in the cells of the oropharynx. The lymph nodes and spleen show lymphocytic infiltration primarily in the periphery of a lymph node.Relative lymphocytosis (≥ 60%) plus atypical lymphocytosis (≥ 10%) are the characteristic findings of Epstein Barr virus (EBV) infectious mononucleosis.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 33 - Which of the following is the most abundant immunoglobulin in plasma: ...

    Incorrect

    • Which of the following is the most abundant immunoglobulin in plasma:

      Your Answer:

      Correct Answer: IgG

      Explanation:

      IgA is the major Ig in secretions, particularly from the gastrointestinal tract (but also in saliva, tears, sweat and breast milk).IgE is important for mast cell degranulation in allergic and antiparasitic response. In the allergic response, the plasma cell produces IgE-antibodies, which, like antibodies of other immunoglobulin isotypes, are capable of binding a specific allergen via its Fab portion.IgG is the most abundant in plasma (comprising 80% of normal serum immunoglobulin) and the main circulatory Ig for the secondary immune response.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 34 - Which of the following best describes a natural killer cell: ...

    Incorrect

    • Which of the following best describes a natural killer cell:

      Your Answer:

      Correct Answer: A large granular lymphocyte that kills by inducing target cell apoptosis.

      Explanation:

      Natural killer (NK) cells are cytotoxic CD8 positive cells that lack the T-cell receptor. They are large cells with cytoplasmic granules. NK cells are designed to kill target cells that have a low level of expression of HLA class I molecules, such as may occur during viral infection or on a malignant cell. NK cells do this by displaying several receptors for HLA molecules on their surface. When HLA is expressed on the target cell these deliver an inhibitory signal into the NK cell. When HLA molecules are absent on the target cell this inhibitory signal is lost and the NK cell can then kill its target. In addition, NK cells display antibody-dependent cell-mediated cytotoxicity. In this, antibody binds to antigen on the surface of the target cell and then NK cells bind to the Fc portion of the bound antibody and kill the target cell.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 35 - Which of the following statements is correct with regards to immunoglobulin? ...

    Incorrect

    • Which of the following statements is correct with regards to immunoglobulin?

      Your Answer:

      Correct Answer: The isotype of immunoglobulin is determined by the heavy chain.

      Explanation:

      The composition of immunoglobulin molecules is two identical heavy and two identical light chains. These chains are linked by disulphide bridges and are each have highly variable regions which give the immunoglobulin its specificity. In addition, they have constant regions and there is virtual complete correspondence in amino acid sequence in all antibodies of a given isotype. Five isotypes of immunoglobulin exist – these are IgG, IgA, IgM, IgE and IgD. They are determined by the heavy chain (gamma, alpha, mu, epsilon or delta respectively). The light chains are either kappa or lambda.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 36 - Which of the following statements about neutrophils is TRUE: ...

    Incorrect

    • Which of the following statements about neutrophils is TRUE:

      Your Answer:

      Correct Answer: Neutrophils are typically the first immune cell to arrive to a site of injury.

      Explanation:

      Neutrophils are the most numerous peripheral blood leukocytes, accounting for 50-70 percent of all circulating white cells. Neutrophils have a compact nucleus with two to five lobes and a pale cytoplasm with an irregular shape containing numerous fine pink-blue or grey-blue granules. The granules are classified as primary, which emerges during the promyelocyte stage, and secondary, which develop at the myelocyte stage and predominate in the mature nucleus.The lifespan of neutrophils in the blood is only 6 – 10 hours. In response to tissue damage, cytokines and complement proteins, neutrophils migrate from the bloodstream to the site of insult within minutes, where they destroy pathogens by phagocytosis.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 37 - Which of the following pathogens is most likely to cause an infection in...

    Incorrect

    • Which of the following pathogens is most likely to cause an infection in a chemo patient with significant neutropenia?

      Your Answer:

      Correct Answer: Candida

      Explanation:

      Chemotherapy that is too aggressive weakens your immune system, putting you at risk for a fungal and many other infection. Neutropenia is a condition in which a person’s neutrophil count is abnormally low. Neutrophils are an infection-fighting type of white blood cell. Neutrophils fight infection by killing bacteria and fungi (yeast) that infiltrate the body. Fungal organisms are significant pathogens in the setting of neutropenia.

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds
  • Question 38 - Regarding cytotoxic T cells, which of the following statements is CORRECT: ...

    Incorrect

    • Regarding cytotoxic T cells, which of the following statements is CORRECT:

      Your Answer:

      Correct Answer: They kill target cells by inducing cell apoptosis.

      Explanation:

      CD8+ T-cells (Cytotoxic T cells)Recognise antigen only in association with HLA Class I molecules (found on all nucleated cells; present endogenous antigens such as those found in cells infected by viruses or intracellular bacteria.)Comprise about 25% of peripheral T-cellsResponsible for cytotoxic killing of target cells

    • This question is part of the following fields:

      • Immune Responses
      • Pathology
      0
      Seconds

SESSION STATS - PERFORMANCE PER SPECIALTY

Immune Responses (8/12) 67%
Pathology (8/12) 67%
Passmed