PBL 4 – ASTRO BOY
1999 Paper 1, Part C: Q8
Question 8.
By means of a diagram explain the role of T and B lymphocytes in immunity.
(5 marks)
1999 Paper 2, Part D: Q6b
Question 6.
(b) List a distinguishing feature of the functions of each of the five (5) major
immunoglobulin classes. (5 marks)
IgG - Constitutes 80% total Ig
- Responsible for specific immunity
- Can cross the placenta
IgM - Penatmer
- Predominates in the early immune response to ‘new’ antigens
- Constitutes 10% of total Ig
IgE - Surface receptor on mast and basophil cells.
- Cross-linking causes histamine release.
- Responsible for allergic reactions.
IgA - Is found in the GIT and in secretions such as mucous, saliva, tears and milk.
- Produced by B-lymphocytes in Peyer’s Patches, tonsils and other submucosal
lymphoid tissues.
- IgA attacks pathogens before they enter the body tissues.
IgD - Is an individual molecular receptor on the surface of B-lymphocytes
(membrane-bound), rarely secreted.
- Physiological function unknown.
- Binds Ag to activate the B-lymphocyte.
2000 Paper 1, Part D: Q8
Question 8. (5 marks)
By means of a diagram explain the role of T and B lymphocytes in immunity.
2001 Paper 2, Part D: Q4, 7
Question 4. (5 marks)
In relation to the function of white cells:
Respond to the following statements as TRUE (T), FALSE (F) OR DON’T KNOW (D)
CIRCLE YOUR CHOICE
1) The neutrophil is the major cell type involved in defence against
pyogenic bacteria. T F D
2) Release of sequestered neutrophils by the spleen is an explanation
for the sharp rise in neutrophil counts in the early stages of an
infection. T F D
3) The granulocyte family encompassing neutrophils, eosinophils and
basophils are all derived from the same stem cell within the bone
marrow. T F D
4) Monocytes share their developmental origins with lymphocytes. T F D
5) Monocytes have a shorter half-life than neutrophils. T F D
6) Monocytes transform into phagocytic macrophages when they leave
the intravascular compartment. T F D
7) Neutrophils use their lysosomes to phagocytose infective agents. T F D
Question 7. (5 marks)
By means of a diagram explain the development and role of T and B lymphocytes in
immunity.
As 1999 Paper 1, Part C: Q8 & 2000 Paper 1, Part D: Q8
2002 Paper 1, Part D: Q7
Question 7. (5 marks)
Respond to the following statements as TRUE (T), FALSE (F) OR DON’T KNOW (D).
CIRCLE YOUR CHOICE
1) Naïve T lymphocytes require two (2) stimulatory signals to become
activated and to proliferate. T F D
2) Dendritic cells are cells that activate naïve B lymphocytes. T F D
3) During B lymphocyte development, B cells rearrange the DNA in the
constant (C) region of the immunoglobulin gene locus. T F D
4) CD4+ T lymphocytes (T helper cells) interact with cells expressing
class I MHC (major histocompatibility complex) molecules but not
with those expressing class II MHC. T F D
5) Cytokines are important in guiding the class of immunoglobulin (Ig)
secreted by a plasma cell. T F D
6) Interleukin-1 is a major cytokine involved in T-cell activation. T F D
7) Interleukin-4 is a major cytokine involved in B-cell activation. T F D
2003 Paper 2, Part D: Q7
Question 7. (10 marks)
By means of a diagram explain the development and role of T and B lymphocytes in
immunity.
As 1999 Paper 1, Part C: Q8; 2000 Paper 1, Part D: Q8 & 2001 Paper 2, Part D: Q7