CSMLS CSMLS Immunology and Serology 1 — Questions and Answers
Question 1: Which immunoglobulin class is the first to be produced during a primary immune response?
- IgM (Correct answer)
- IgG
- IgA
- IgE
Correct answer: IgM
IgM is the first antibody produced during a primary immune response due to its pentameric structure enabling early complement activation.
Question 2: In an enzyme-linked immunosorbent assay (ELISA), the signal is generated by:
- A radioactive isotope
- An enzyme conjugated to an antibody (Correct answer)
- A fluorescent dye attached to antigen
- A complement protein
Correct answer: An enzyme conjugated to an antibody
In ELISA, an enzyme-conjugated antibody reacts with a substrate to produce a measurable colorimetric, fluorescent, or luminescent signal.
Question 3: The complement pathway initiated by antigen-antibody complexes is the:
- Lectin pathway
- Alternative pathway
- Classical pathway (Correct answer)
- Propyl pathway
Correct answer: Classical pathway
The classical complement pathway is activated by antigen-antibody (immune) complexes binding to C1q.
Question 4: A prozone phenomenon in agglutination testing occurs when:
- Antigen is in excess causing false-negative results
- Antibody is in excess causing false-negative results (Correct answer)
- Temperature is too high
- pH is too acidic
Correct answer: Antibody is in excess causing false-negative results
The prozone effect occurs when antibody excess prevents lattice formation, resulting in a false-negative agglutination reaction.
Question 5: Which serological test is the gold standard for confirming HIV infection?
- ELISA
- Western blot (Correct answer)
- Latex agglutination
- Immunofluorescence
Correct answer: Western blot
Western blot is used as the confirmatory test for HIV infection because it detects antibodies to specific viral proteins.
Question 6: HLA typing in transplantation medicine is performed to:
- Detect blood group antigens
- Match donor and recipient tissue antigens to reduce rejection (Correct answer)
- Identify ABO incompatibility
- Screen for autoimmune disease
Correct answer: Match donor and recipient tissue antigens to reduce rejection
HLA (human leukocyte antigen) typing matches major histocompatibility complex antigens between donor and recipient to minimize transplant rejection.
CSMLS CSMLS Immunology and Serology 1
Which immunoglobulin class is the first to be produced during a primary immune response?