Immunology Flashcards
Major Histocompatibility complex (MHC) class II antigens are expressed by:
A. Renal tubular cells
B. Erythrocytes
C. Antigen presenting cells
D. Hepatocytes
E. Osteoclasts
Answer: C - antigen presenting cells
Which one of the following options correctly describes these 3 primary immunodeficiencies?
1 - DiGeorge syndrome, 2- Chronic granulomatous disease, 3 -severe combined immunodeficiency
Options: Defects in neutrophils, defects in lymphocytes, absent thymus
Answer:
DiGeorge syndrome - absent thymus
Chronic granulomatous disease - defects in neutrophils
Severe combined immunodeficiency - defects in lymphocytes
Toll-like receptors function in which one of the following?
A. Regulation of B-cell activation by antigen binding
B. Activation of the complement pathway
C. Recognition of microorganisms by the innate immune system
D. Activation of Ig chain switching
E. Inhibition of eosinophils
Answer: C - Recognition of microorganisms by the innate immune system
Which one of the following is an advantage of killed viral vaccines compared to live vaccines?
A. Killed vaccines produce a CD8 cytotoxic T cell response
B. Killed viral vaccines can be given by the natural route of infection and induce an IgG and IgA response
C. Killed viral vaccines often confer life-long protection
D. Killed viral vaccines do not revert to virulence
E. Killed viral vaccines can be given pre-exposure to disease-causing agents
Answer: D - Killed viral vaccines do not revert to virulence
Which one of the following is the main difference between cytotoxic type II and immune complex type III hypersensitivity?
A. Distribution of antigen-antibody complexes
B. Involvement of T cells
C. Involvement of complement
D. Antibody isotype
E. Difference in triggers
Answer: A - Distribution of antigen-antibody complexes
Type 2 hypersensitivity is known as cytotoxic hypersensitivity. The antigens are usually endogenous (although haptens can cause). It is primarily mediated by IgM or IgG and complement.
Type 3 hypersensitivity is also known as immune complex hypersensitivity. The reaction can be general (serum sickness) or individual organs (SLE, Arthus reaction), blood vessels (polyarteritis), joints (RA). THe reaction may take 3-10hours after exposure (as in Arthus reaction). It is mediated by soluble immune complexes (usually IgG).
Which one of the following correctly describes IgA in humans?
A. Rarest Ig isotype
B. 2 subclasses IgA1 and IgA2 differ in their light chains
C. IgA2 is present more abundantly than IgA1 in airways
D. Secretory IgA can reduce motility of salmonella and reduce virulence
E. IgA2 is the predominant subclass in serum
Answer: D - Secretory IgA can reduce motility of salmonella and reduce virulence
IgA is the most abundant immunoglobulin isotype (production exceeds all others combined). IgA1 and 2 differ in heavy chains. IgA1 is predominant in airways and serum, IgA2 in the colon.
Which one of the following describes the involvement of human natural killer NK cells in innate immunity?
A. NK cells are directly activated by macrophages
B. NK cells express antigen specific receptors
C. NK cells contribute to delayed T cell response following infection
D. NK cells do not mediate antibody dependent cell cytotoxicity
E. NK cells are only found in lymph nodes
Answer: C - NK cells contribute to delayed T cell response following infection
NK cells are innate immune system cells that destroy infected and malignant cells. They are identified by CD56 and a lack of CD3. They are an important source of immunoregulatory cytokines including IFN, TNF, GM-CSF which coordinate the early immune response and contribute to delayed T cell response.
A 24 year old man is stung by a bee and experiences respiratory distress within minutes and lapses into unconsciousness. This reaction is probably mediated by:
A. IgG antibody
B. IgE antibody
C. IgM antibody
D. Complement
E. Sensitised T cells
Answer: B - IgE antibody
Which one of the following is a mechanism in the development of immune tolerance?
A. Clonal amplification of B cells in the thymus
B. Failure of B cells bearing low-affinity receptors to recognise self-antigens in the thymus
C. T cells in the thymus with high affinity for self-antigen undergo positive selection
D. Regulatory T cells actively activate an immune response to an antigen
E. Acquisition of anergy after T-cell receptor ligation without co-stimulation
Answer: E - anergy of T cells without co-stimulation
A 56 year old bee farmer was admitted after an anaphylactic reaction to bee stings. He underwent immunotherapy/desensitisation to prevent future adverse reactions associated with bee stings. Which one of the following mechanisms explains the principle of immunotherapy?
A. Reduces allergen-specific IgE
B. Acts by induction of ‘blocking’ IgG antibodies
C. Works by altering T-cell reactivity to specific antigen, which in turn causes a reduction in release of pro-allergic/inflammatory cytokines
D. Works by inactivating B cells, which then alters T-cell reactivity to the specific antigen
E. Acts by blocking the antigen-presenting cells directly, so the foreign antigen is not detected by the immune system of the patient
Answer: C - W orks by altering T-cell reactivity to specific antigen, which in turn causes a reduction in release of pro-allergic/inflammatory cytokines
Immunotherapy works by altering T-cell responses to specific antigens. Serious reactions occur at a rate of 1 in 500.
Interferon-gamma is produced by:
A. Type 1 helper T cells
B. Type 2 helper T cells
C. B lymphocytes
D. Plasma cells
E. Eosinophils
Answer: A - Type 1 helper T cells
Th1 cells secrete IFN-gamma inducing a cellular response
Th2 cells secrete IL-4 (activating B cells) and TGF-B and IL-10
EMQ
A. Neutrophils
B. Eosinophils
C. B lymphocytes
D. T lymphocytes
E. Macrophages
F. Dendritic cells
G. Natural killer cells
H. Plasma cells
- Which cell is the main source of IL-1?
- Which cell is the main source of IL-2?
- Answer: E - Macrophages produce IL-1 and TNF
- Answer: D - T lymphocytes produce IL-2 to promote T lymphocyte population expansion
A 24 year old man with a history of hereditary angioedema (HAE) presents with acute dyspnoea and on examination has laryngeal, pharyngeal and tongue oedema. In addition to securing his airway, which drug should be administered urgently?
A. IV Methylprednisolone
B. IV Furosemide
C. Anti-histamine
D. Fresh frozen plasma
E. Nebulised salbutamol
Answer: D - FFRP
FFP contains C1-inhibitor concentrate and can be used when C1 inhibitor is not available.
HAE is an autosomal dominant genetic disorder with loss of C1 inhibitor or its activity.
C1 inhibitor, as well as its complement functions, inhibits kallikrein from which bradykinin is derived. C1 inhibitor loss of function leads to excess kallikrein and angioedema attacks.
In acute attacks, larygenal swelling can occur in isolation or with swelling of the lips, tongue, uvula and soft palate. Diagnosis is by demonstration of low C1 inhibitor concentration or function.
Treatments for acute episodes include purified C1 inhibitor (Berinert) or bradykinin receptor antagonist Icatibant.
A 20 year old woman presents with dyspnoea, angioedema, urticaria and hypotension after eating shellfish. She is successfully treated with adrenaline, antihistamines, corticosteroids and IV fluids. She has a history of asthma and takes inhaled beclomethasone. RAST reveals shellfish-specific IgE. Which one of the following statements is most accurate?
A. The allergy is likely to disappear in a few years
B. She should avoid other highly allergenic foods such as peanuts and tree nuts
C. She is at high risk of a more severe anaphylactic reaction in future if she ingests shellfish
D. She had a type II hypersensitivity reaction
E. She had a type IV hypersensitivity reaction
Answer: C - She is at high risk of a more severe anaphylactic reaction in future if she ingests shellfish
Risk factors for severe anaphylaxis include:
- Previous anaphylaxis
- Asthma, especially if poorly controlled
- Peanut allergy, fish or shellfish allergy
- Possibly worse in females
Allergies to tree nuts and fish are generally not outgrown and persist through life.
A 30 year old Aboriginal woman received a tetanus vaccination today. She had her DtPA injection following the birth of her first child. She asks whether she should have any other immunisations. Which one of the following is recommended for ATSI populations?
A. Pneumococcal and annual influenze for ATSI >15 years
B. Annual influenza for ATSI >50yrs
C. Pneumococcal and annual influenza for all ATSI >65yrs
D. Pneumococcal >50yrs and annual influenza >65yrs
E. Annual influenza >50yrs and pneumococcal >65 years
Answer: B - Annual influenza vaccination for all Aboriginal/Torres Strait islanders over age of 50 years
Influenza recommended for all above age of 65 and ATSI above 50.
Pneumococcal recommended for:
- All over age of 65
- ATSI over age of 50yrs
- Asplenia
- Immunocompromised incl. HIV, nephrotic syndrome, myeloma, lymphoma or transplant
- Risk of pneumococcal disease from chronic illness
- CSF leak
