Medical Laboratory Technician Exam FREE Medical Laboratory Technician Immunology and Serology Questions and Answers 2 — Questions and Answers
Question 1: Which immunoglobulin class is most abundant in serum and provides the majority of antibody-based immunity against invading pathogens?
- IgG (Correct answer)
- IgM
- IgA
- IgE
Correct answer: IgG
IgG is the most abundant immunoglobulin in serum, comprising approximately 75-80% of total serum immunoglobulins.
Question 2: In a direct antiglobulin test (DAT), what does a positive result indicate?
- Antibodies or complement are bound to the surface of red blood cells in vivo (Correct answer)
- Free antibodies are present in the patient's serum
- The patient has an active bacterial infection
- Complement levels are critically low
Correct answer: Antibodies or complement are bound to the surface of red blood cells in vivo
A positive DAT indicates that antibodies or complement components have attached to red blood cells in the patient's circulation.
Question 3: Which complement pathway is activated by antigen-antibody complexes involving IgG or IgM?
- Classical pathway (Correct answer)
- Alternative pathway
- Lectin pathway
- Terminal pathway
Correct answer: Classical pathway
The classical complement pathway is initiated when C1q binds to antigen-antibody complexes containing IgG or IgM.
Question 4: A patient presents with recurrent Neisseria infections. Which complement component deficiency is most likely?
- C5-C9 (membrane attack complex) (Correct answer)
- C1 esterase inhibitor
- C3
- Factor B
Correct answer: C5-C9 (membrane attack complex)
Deficiencies in terminal complement components C5-C9 are strongly associated with recurrent Neisseria infections due to impaired bactericidal activity.
Question 5: What is the principle behind nephelometry as used in clinical immunology laboratories?
- Measurement of light scattered by antigen-antibody complexes in solution (Correct answer)
- Measurement of light absorbed by colored enzyme substrates
- Detection of fluorescent-labeled antibodies on cell surfaces
- Quantification of radioactive isotope decay from labeled antigens
Correct answer: Measurement of light scattered by antigen-antibody complexes in solution
Nephelometry measures the intensity of light scattered by immune complexes formed in solution to quantify specific proteins.
Question 6: Which serological test is considered the confirmatory test for HIV infection after a reactive screening immunoassay?
- HIV-1/HIV-2 antibody differentiation immunoassay (Correct answer)
- Western blot only
- Rapid plasma reagin (RPR)
- Monospot test
Correct answer: HIV-1/HIV-2 antibody differentiation immunoassay
Current CDC-recommended algorithms use an HIV-1/HIV-2 antibody differentiation immunoassay as the supplemental test following a reactive initial immunoassay.
Medical Laboratory Technician Exam FREE Medical Laboratory Technician Immunology and Serology Questions and Answers 2
Which immunoglobulin class is most abundant in serum and provides the majority of antibody-based immunity against invading pathogens?