ASCP Immunology and Serology 1 — Questions and Answers
Question 1: The VDRL and RPR tests are nontreponemal screening tests for which disease?
- Lyme disease
- Syphilis (Correct answer)
- HIV infection
- Hepatitis B
Correct answer: Syphilis
VDRL and RPR detect cardiolipin-lecithin antibodies (reagin) produced in response to Treponema pallidum infection.
Question 2: Which immunoglobulin class is the first produced in a primary immune response?
- IgG
- IgA
- IgM (Correct answer)
- IgE
Correct answer: IgM
IgM is the first antibody class produced during a primary immune response due to its rapid synthesis from B-cell activation.
Question 3: A positive ANA (antinuclear antibody) test is most associated with which autoimmune disease?
- Rheumatoid arthritis
- Systemic lupus erythematosus (SLE) (Correct answer)
- Ankylosing spondylitis
- Sjögren's syndrome alone
Correct answer: Systemic lupus erythematosus (SLE)
ANA is positive in >95% of SLE patients; anti-dsDNA and anti-Sm are specific confirmatory tests for SLE.
Question 4: ELISA (enzyme-linked immunosorbent assay) is used as the initial test for HIV diagnosis because:
- It is the most specific test available
- It has high sensitivity to minimize false negatives (Correct answer)
- It can detect viral RNA directly
- It requires no confirmatory testing
Correct answer: It has high sensitivity to minimize false negatives
ELISA has high sensitivity for HIV antibody detection, minimizing missed infections; reactive results are confirmed by Western blot or HIV-1/2 differentiation assay.
Question 5: Rheumatoid factor (RF) is an antibody directed against:
- Double-stranded DNA
- The Fc portion of IgG (Correct answer)
- Cyclic citrullinated peptides
- Cardiolipin
Correct answer: The Fc portion of IgG
Rheumatoid factor is typically an IgM antibody that binds the Fc region of IgG; it is elevated in rheumatoid arthritis and other inflammatory conditions.
Question 6: Which hepatitis B marker indicates active viral replication and high infectivity?
- HBsAg alone
- Anti-HBs
- HBeAg (Correct answer)
- Anti-HBc IgG
Correct answer: HBeAg
HBeAg is a secreted antigen associated with active viral replication and correlates with high HBV DNA levels and greater infectivity.
ASCP Immunology and Serology 1
The VDRL and RPR tests are nontreponemal screening tests for which disease?