CMLA Immunology & Serology 1 — Questions and Answers
Question 1: What type of immunity is acquired through vaccination?
- Natural passive immunity
- Artificial active immunity (Correct answer)
- Natural active immunity
- Artificial passive immunity
Correct answer: Artificial active immunity
Vaccination introduces antigens artificially to stimulate the body's own immune system to produce antibodies, which is classified as artificial active immunity.
Question 2: Which immunoglobulin is the most abundant in serum and provides long-term immunity?
- IgM
- IgA
- IgG (Correct answer)
- IgE
Correct answer: IgG
IgG is the most abundant immunoglobulin in serum (~75-80% of total), provides long-term immunity, and is the only class that crosses the placenta.
Question 3: Which complement pathway is activated by antigen-antibody (immune) complexes?
- Alternative pathway
- Lectin pathway
- Classical pathway (Correct answer)
- Properdin pathway
Correct answer: Classical pathway
The classical complement pathway is initiated when C1q binds to antigen-antibody complexes, triggering the complement cascade.
Question 4: What is the primary function of B lymphocytes in the immune response?
- Direct cytotoxic cell killing
- Antibody (immunoglobulin) production (Correct answer)
- Phagocytosis of pathogens
- Regulation of T cell activity
Correct answer: Antibody (immunoglobulin) production
B lymphocytes differentiate into plasma cells that produce antigen-specific antibodies (immunoglobulins), mediating humoral immunity.
Question 5: Which type of hypersensitivity reaction is mediated by IgE antibodies and occurs immediately upon antigen exposure?
- Type II (cytotoxic)
- Type III (immune complex)
- Type IV (delayed)
- Type I (anaphylactic) (Correct answer)
Correct answer: Type I (anaphylactic)
Type I hypersensitivity is mediated by IgE antibodies bound to mast cells and basophils; cross-linking by antigen triggers immediate degranulation.
Question 6: Which immunoglobulin is the first to be produced during a primary immune response?
- IgG
- IgA
- IgM (Correct answer)
- IgD
Correct answer: IgM
IgM is the first antibody produced in a primary immune response; its pentameric structure provides efficient early defense before class switching to IgG occurs.
Question 7: An antigen is best defined as a substance that:
- Is produced by plasma cells to neutralize pathogens
- Stimulates an immune response and binds specifically to antibodies (Correct answer)
- Activates phagocytes to engulf foreign material
- Provides non-specific innate immune defense
Correct answer: Stimulates an immune response and binds specifically to antibodies
An antigen is any molecule that stimulates an immune response and can bind specifically to the antibodies or T-cell receptors it elicited.
CMLA Immunology & Serology 1
What type of immunity is acquired through vaccination?