Test 126 (Immunology)
1.  Immunoglobulins:
a. contain antigen-binding sites derived from both the 
    heavy and light chains.

b. contains Fc regions derived solely from the heavy 

c. are chiefly of Ig E class at mucosal surfaces

d. are produced by both T and B lymphocytes

e. of Ig E class give protection against parasitic worms.

2. Opsonization:

a. is mediated by complement components.

b. enhances phagocytosis

c. involves mainly the Fc protion of the immunoglobulins

d. involves fibronectin

e. is not restricted by the MHC (Major Histocompatiblity 

3. IgG:

a. has a molecular weight of 50,000 kd.

b. is monvalent

c. comprises the majority of circulating antibody in serum

d. differs from other isotypes in being ablt to cross the 
    placental barrier

e. is the major antibody produced during the primary 

4. For antigen presentation to CD4+ T lymphocytes:

a. antigen is processed via the endogenous pathway

b. specialised antigen presenting cells are required for the 
    induction of the T cell immune response

c. Short antigen-derived peptides associate with MHC 
    class II molecules in the endoplasmic reticulum

d. exogenously added synthetic peptide corresponding to 
    the antigenic epitope can substitute for processed 
    antigen for T cell recognition. 

e. the antigen must be synthesised within the antigen 
    presenting cell in order to be processed and presented 
    by MHC

5. In the thymus:

a. the majority of cortical thymocytes express either CD4 
    or CD8.

b. CD4/CD8 double positive cells are eliminated by a 
    process of negative selection.

c. a proportion of alpha/beta+ thymocytes undergo 
    isotype switching to produce gamma/delta+ T cells.

d. thymocytes whose TcR bind with high affinity to self  
    Ag/MHC complexes are clonally detected.

e. mature thymocytes express surface IgM and IgD

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