DMF MSE 2 2007
Which one of the following statements about antibody gene rearrangement is correct?
Antibody gene rearrangement predominantly involves CH genes
Antibody gene rearrangement selects for high affinity antibodies
Antibody gene rearrangement only occurs after antigen stimulation
Antibody gene rearrangement is required to create functional antibody genes
Antibody gene rearrangement requires T cell help
Which one of the following statements about HLA molecules is correct?
HLA molecules generate receptor diversity by gene rearrangement
HLA polymorphism affects antigen recognition by T cells
HLA molecules undergo somatic hypermutation
Mature T cells bind HLA molecules with very high affinity
HLA Class II molecules are expressed by almost all nucleated cells
The activation of T and B cells is the central process of the adaptive immune system. Which one of the statements below correctly describes features in the activation process which are shared by both T and B cells?
Many different antigens may activate individual T or B cells
Both T and B cell receptors only recognise antigens derived from pathogens
Both T and B cells are activated in infected tissues
Antigen processing by both dendritic cells and macrophages activates both T and B cells
Both T and B cells circulate through lymphoid tissues where they encounter antigen
Which one of the statements below concerning antigen presenting cells is correct?
Antigen presenting cells may influence the differentiation pathway of T helper cells they are activating
Class I and Class II MHC molecules associated with antigen presenting cells predominantly bind foreign peptides
Antigen presenting cells display antigens which are derived exclusively from the cytosol on MHC Class II antigens
Activated antigen presenting cells are retained in infected tissues to defend against invading pathogens
The co-stimulatory molecules CD80 and CD86 are constitutively expressed on antigen presenting cells
CD8 Cytotoxic T cells and Natural Killer (NK) cells possess several shared characteristics. Select the characteristic described below which is not shared by both cell types
Cytotoxic T cells and NK cells kill their target cells using perforin and granzymes
Individual cytotoxic T cells and NK cells bind Class I MHC molecules on target cells
Individual cytotoxic T cells and NK cells kill cells infected by several different viruses
Activated cytotoxic T cells and NK cells can secrete interferon gamma
Cytotoxic T cells and NK cells do not kill uninfected target cells
Which one of the following statements about the pathogenesis of diseases caused by immune responses is incorrect?
Systemic lupus erythematosis (SLE) is characterised by deposition of antigen – antibody complexes in synovium, small blood vessels and glomeruli
Antibodies against nuclear antigens may contribute significantly to the pathogenesis of SLE
Antibodies against gliadin may contribute significantly to the pathogenesis of coeliac disease
Animal models of insulin dependent diabetes mellitis (IDDM) suggest that islet cell damage is due to a destructive T cell response
Infections of particular tissues may result in the expression of costimulatory molecules on antigen presenting cells leading to the breakdown of T cell tolerance to self antigens
Which one of the following statements below is
Encounter with antigen during T cell differentiation in the thymus typically results in clonal anergy
Clonal anergy involves a state of non-responsiveness to specific antigen by lymphocytes
Clonal anergy involves ignorance of antigen by specific T lymphocytes
Clonal anergy involves malignant transformation of aberrant lymphocytes
Clonal anergy involves specific apoptosis of self-reactive T cells
Which one of the following statements about immediate (Type I) hypersensitivity reactions is correct?
Individuals who are atopic will display the symptoms of Type I hypersensitivity immediately after their first exposure to a particular allergen
Type I hypersensitivity reactions are predominantly mediated by IgE which is secreted by plasma cells in response to interferon gamma stimulation
Type I hypersensitivity reactions are predominantly mediated by degranulation of mast cells which have bound complement and allergen
Type I hypersensitivity reactions are predominantly mediated by crosslinking of IgE bound FcRε on the surface of mast cells by allergen
Type I hypersensitivity reactions are predominantly mediated by complexes of IgE and antigen which form in submucosal tissues and subsequently bind mast cells
Which one of the following statements about mast cells is incorrect?
Mast cells contain histamine that is rapidly released upon degranulation.
Mast cells bind IgE through high affinity cell surface receptors.
Mast cells make and release cysteinyl leukotrienes.
Mast cells are targets for the anti-allergic actions of anti-histamines.
Mast cells are targets for anti-allergic actions of disodium cromoglycate.
Which one of the following statements about vaccines is correct?
An advantage of inactivated vaccines is that they produce a longer-lived response than live attenuated vaccines do
MMR vaccine is safe to use in immunocompromised individuals
A conjugated vaccine is one where different polysaccharide antigens from related organisms are chemically linked together
The hepatitis B vaccine is a live attenuated vaccine
The efficacy of immunisation with a live attenuated viral vaccine may be compromised by the presence of circulating antibodies
Tania Plotkin, a sixteen year old girl, was investigated for an immune deficiency
because of a history of recurrent infections.
On investigation, her levels of immunoglobulins and complement components were normal. Assays for antibodies to vaccine antigens showed normal levels of antibodies to these antigens. Her neutrophil numbers and function were also normal.
Tania’s T cell numbers, as determined by measuring the number of cells expressing CD3, were found to be normal. B cell numbers were also normal and they expressed MHC Class II antigens. However, Tania’s lymphocytes and other nucleated cells did not express MHC Class I antigens.
Which one of the following would be consistent with these laboratory data?
Tania’s lymphocytes are normal in number and function
Tania would be likely to be unable to control infections with capsulated bacteria
Tania would be likely to be deficient in helper T cells
Tania’s helper T cells would be unable to secrete gamma-interferon
Tania would be likely to be deficient in cytotoxic T cells
Which one of the following statements concerning increased vascular permeability associated with acute inflammation is incorrect?
Oedema first develops in acute inflammation due to the formation of a high protein transudate (Specific Gravity > 1.020)
An immediate, sustained increase in permeability is likely to be mediated by direct endothelial cell injury
Histamine release is likely to produce an immediate, transient pattern of increased permeability of post-capillary venules
An immediate, transient pattern of increased permeability is likely to involve receptor-mediated contraction of endothelial cells
A delayed increase in permeability may be mediated via cytokines such as TNF alpha
Which one of the following statements concerning cells associated with acute inflammation is incorrect?
Neutrophils migrating into the tissues survive for only 4 to 6 hours
Eosinophils contain histaminase which assists in terminating the acute inflammatory response
Neutrophil myeloperoxidase helps to protect tissues from injury caused by peroxides released from activated phagocytes
The immature neutrophils found in the circulation in association with an acute inflammatory response are known as "band forms"
Complement component C5a is a chemotactic factor for neutrophils
One of the currently licensed vaccines against Streptococcus pneumoniae which is designed to induce protection against invasive pneumococcal disease is prepared from chemical conjugates of pneumococcal surface polysaccharides and a protein such as tetanus toxoid. Which one of the statements below correctly describes the features of this vaccine?
It induces an immune response which targets all strains of Streptococcus pneumoniae
It acts by eliciting antibodies that block the ability of pneumococcal polysaccharides to trigger the complement cascade
Regular boosters (every 1 – 2 years) would be required to maintain the vaccine response
It only induces immunity in adolescents and adults
It induces isotype switching by antigen-activated B cells
A 17 year old girl presented to the emergency department of a teaching hospital with a one day history of headache, fever and photophobia. She had previously been well and had received all of her immunisations. CSF and blood cultures were collected and IV cefotaxime was administered. 45 minutes later the laboratory reported the following CSF results: 1140 leucocytes/μl (90% polymorphonuclear leukocytes); protein 2.0g per litre (normal < 0.4g/l); glucose 1.7mmol/l (normal ≥ 2.5 mmol/l); Gram negative diplococci seen on Gram stain; Latex agglutination tests for H. influenzae type b and Neisseria meningitidis were negative. On the basis of the test results, which one of the following infectious agents listed below is the most likely cause of her condition?
When confronted with an angry patient, which one of the following is least likely to be correct?
It is never appropriate to end the interaction
The anger usually reflects a severe personality problem in the patient
Anger is never related to uncertainty or lack of information
There are no limits to what is an acceptable level of aggression that can be expressed in a doctor patient interaction
Angry outbursts usually have little emotional effect on professionals.
When managing a tearful patient which statement is least likely to be correct?
The most common cause of crying is a mental illness
Acknowledging the patient’s distress does not inevitably make it worse
Resident doctors find tearful patient difficult to manage because they are unsure how to respond
Communicating an understanding of the patient’s concerns may help alleviate distress in some cases
A patient’s emotional distress may be related to the physical symptoms of their illness
When faced with a distressed family member, which statement is least likely to be correct?
Dealing with a distressed family member is a role the treating doctor may undertake
It is sometimes important to acknowledge when things have gone wrong
The doctor should never express uncertainty about the prognosis
Family members may have different concerns from that of the patient
Distressed family members are usually angry with the medical care
Which one of the following changes will result in a significant fall in prevalence of gonorrhoea in a population with a high rate of gonorrhoea among heterosexuals?
A 30% reduction in the mean number of sexual partners per year in this population (standard deviation remains constant)
A significant increase in testing and treatment of women in the non core group
A significant reduction in the number of sexual acts per sexual partnership
Significantly greater access to sexual health services for the population
The introduction of abstinence only before marriage campaign in schools in that community
Unsure if this is correct.
Which one of the following is least effective in reducing the prevalence of STIs (sexually transmissible infections)?
Screening the non-core core group for STIs
Developing a primary care focus on detecting and treating symptomatic patients.
Testing for other STIs when a patient presents with one STI
Screening partners of patients presenting with STIs
Increasing the rate of condom use
The number of secondary infections that arise from one infectious case of a particular disease may be increased by which one of the following factors?
Widespread use of an effective vaccine in the population.
Treatment that controls the symptoms but not the excretion of the infectious agent
Rapid progression of the disease from infection to severe illness
A recent epidemic of the disease in the population
Low population density
Which one of the following factors favours the eradication of an infectious disease of humans?
Chronic human infections occur
The infection is mainly a disease of animals
Clinical illness is mild and indistinct
The available vaccine is stable across a wide range of temperatures
The causative organism forms spores in the natural environment