DMF MSE 2 2011

1

Which one of the following statements best describes the role of C3b?


  It is an important chemotactic molecule for phagocytes

  It polymerizes to form the membrane attack complex

  It initiates the lectin pathway of the complement cascade

  It facilitates the removal of immune complexes

  It is not involved in the alternative complement pathway

2

Which one of the following statements best describes a feature shared between cells of the innate and adaptive immune systems?


  The binding of shared molecular patterns on microbes (e.g. peptidoglycan) to ligands on both groups of cells induces their activation

  Both groups of cells require activation to induce their function

  Both groups of cells interact with microbial components in lymphoid tissues

  Both groups of cells display a greater response when encountering the same microbial components during a second exposure

  Both groups of cells undergo significant proliferation after interaction with microbial components

3

Which one of the statements below best describes the features of Class I MHC antigens?


  They are usually expressed only on dendritic cells, B cells and macrophages

  They bind peptides only after they have been transported to the cell surface

  They can bind short self-peptides whose sequence contains the appropriate anchor residues

  They bind peptides that are derived from antigens that are processed in endosomal compartments

  Their polymorphism is generated by random gene rearrangements during foetal development

4

A mature dendritic cell that expresses co-stimulatory molecules and secretes IL-12 presents an antigen to a CD4 T cell that has a TCR able to bind the MHC Class II-peptide complex. Which one of the statements below best describes the likely outcome of this encounter?


  The effector T cells that are produced will be effective in controlling parasite infections

  The effector T cells that are produced will secrete IFN-gamma and facilitate macrophage activation

  The effector T cells that are produced will secrete IL-6 and IL-17 and facilitate neutrophil activation

  The effector T cells that are produced will produce granules containing perforin and granzymes and secrete IFN-gamma

  The T cells will be anergised

5

James Johnstone is an 18 month old boy who has been diagnosed with pneumonia due to Pneumocystis jiroveci infection.
Further investigations show that he has normal numbers of circulating leucocytes, including T and B cells.
He has normal levels of complement, however his plasma contains abnormally high levels of IgM and only trace levels of IgG and IgA for his age.
He is blood group “O” and has been vaccinated with triple-antigen vaccine.
Further tests of his immune function were undertaken. Which one of the following statements correctly describes a result you would expect from these tests?


  Red blood cell antibodies would be detected in his serum

  His serum would contain high levels of antibodies against tetanus toxoid

  He would have undetectable levels of CD8 T cells

  He would be found to have a defect in the genes encoding the RAG enzymes

  His CD4 T cells, when activated in vitro, would bind soluble CD40 protein

6

Three children from the same family have been referred to the Immunology Department in a Children’s Hospital because they have all had multiple serious virus infections for most of their lives. Analysis of their leucocytes shows that they have normal numbers of all types, including neutrophils, monocytes, NK cells, B cells, CD8 and CD4 T cells. The levels of complement and antibodies in the patients’ blood were all normal. Which one of the following would best explain the patients’problem?


  A failure to express Class I MHC molecules on tissue cells

  A lack of phagocytic cells

  A lack of eosinophils

  A defect in the genes that produce interleukin 4

  A defect in genes that produce perforin and granzymes

7

Which one of the following antibody isotypes is correctly paired with its function?


  IgA: effective in activation of the complement cascade

  IgD: important in defence against parasites

  IgE: inserted into mast cell membranes

  IgG: can induce antibody dependent cellular cytotoxicity

  IgM: crosses the placenta to provide foetal protection

8

Select the correct statement about the events that take place during maturation of T cells in the thymus:


  CD4/CD8 double positive T cells that do not bind self-MHC molecules are selected

  CD4 positive T cells that recognize class I MHC molecules are selected

  Only those T cells that bind self-MHC and self peptides are deleted

  The T cells that leave the thymus bind self MHC Class I molecules with high affinity

  Defective thymic MHC Class II expression would result in an excess of CD8 T cells in the circulation

9

A 2-year old boy is seen by a paediatrician because of his failure to thrive and recurrent bouts of diarrhoea and stomach discomfort. After negative investigations for infectious causes, a jejunal biopsy was performed - this revealed villous atrophy, with hyperplasia of the crypts and excess intestinal mononuclear cells.
Which one of the following would be a likely clinical finding in this patient?


  Glomerulonephritis

  Chronic wheezing

  An urticarial rash

  The presence of antibodies of the IgA class against tissue transglutaminase

  A strong likelihood of the patient’s B cells expressing HLA B57

10

In many autoimmune diseases there is a predominant form of immune response associated with tissue damage. Which one of the following statements best describes this association?


  Cardiac damage in rheumatic fever is predominantly due to reactive oxygen species released from neutrophils in response to streptococcal PAMPs

  Activation of complement and phagocytes by deposited immune complexes is the predominant cause of glomerulonephritis in systemic lupus erythematosus

  Pathology in celiac disease is predominantly due to the production of antibodies against gliadin

  Disease in myasthenia gravis is predominantly due to autoantibodies that stimulate acetyl choline receptor function

  Autoimmune haemolytic anaemia is predominantly due to perforin induced erythrocyte lysis by cytotoxic T cells

11

The effectiveness of glucocorticoids as anti-allergy drugs is best explained by which one of the following options?


  Suppression of cytokine synthesis

  Suppression of histamine synthesis

  Suppression of cysteinyl-leukotriene synthesis

  Both A) and B)

  Both A) and C)

12

Which one of the following statements regarding vaccines is correct?


  Compared with living attenuated vaccines, killed vaccines are more likely to stimulate both cell-mediated and humoral immunity

  Factors that influence the immunisation schedules in different countries include: the age at which the infection is most likely to occur, the presence of maternal antibodies, and whether the vaccine is living or inactivated

  A disadvantage of living attenuated vaccines compared with killed vaccines is that most living vaccines need to be given with strong adjuvants to be effective

  A disadvantage of inactivated polio vaccine (Salk) is that it may occasionally mutate to become virulent

  Killed vaccines, such as inactivated oral polio vaccine, may fail if the vaccine recipient is infected with another virus at the time they receive the vaccine

13

A 5 year old girl was taken to her GP with headache and fever. She had mild photophobia and neck stiffness. She had previously been well and had received all of her immunisations. The GP administered intramuscular benzyl penicillin, and the girl was sent to the emergency room of a nearby teaching hospital.
CSF obtained via lumbar puncture on her arrival at hospital contained 260 lymphocytes/цl, 35 polymorphonuclear leukocytes/цl, and 0.5 g protein per litre (normal < 0.4 g/l); glucose was normal.
Which one of the infectious agents listed below is the most likely cause of her condition?


  Neisseria meningitidis

  Streptococcus pneumoniae

  Enterovirus

  Influenza virus

  Mycobacterium tuberculosis

14

Which one of the following statements about viruses is correct?


  Some viruses have an envelope which protects their capsid from degradation

  Receptors on the virus surface define which cell types can be infected

  Viruses with RNA genomes must bring an RNA- dependent RNA polymerase protein into the cell as part of the virion

  Most viruses with DNA genomes can use host cell polymerases to replicate

  Non-enveloped viruses can enter the cell by either fusion at the cell surface or by endocytosis

15

Which one of the following statements regarding inflammatory cells is INCORRECT?


  Basophils bind IgE and degranulate to release histamine

  Activated neutrophils are short-lived because they are often recruited into areas with a poor oxygen supply

  Eosinophils release Major Basic Protein, which is cytotoxic for epithelial cells

  Neutrophil myeloperoxidase utilises superoxide radicals in the respiratory burst

  Mast cells originate from the bone marrow, but can also proliferate in the tissues