Medical Laboratory Technician Exam Immunology and Serology 2

Question 1

Which complement pathway is activated by mannose-binding lectin (MBL) binding to microbial carbohydrates?

Accepted Answer

Lectin pathway

Answer

MBL activates the lectin (MBL) pathway by binding mannose residues on microbial surfaces, triggering MASP-1 and MASP-2.

Question 2

A patient's serum shows a prozone phenomenon in an RPR test. What should the laboratory do?

Accepted Answer

Dilute the serum and repeat the test

Answer

Prozone occurs with antibody excess; diluting the serum allows lattice formation and produces a visible agglutination reaction.

Question 3

Which cell type is the primary producer of IgE antibodies in allergic responses?

Accepted Answer

Plasma cells derived from B lymphocytes

Answer

IgE is secreted by plasma cells (terminally differentiated B cells) after class-switching driven by IL-4 and IL-13.

Question 4

In a direct antiglobulin test (DAT), a positive result with anti-IgG but negative with anti-C3d most likely indicates:

Accepted Answer

Warm autoimmune hemolytic anemia

Answer

Warm AIHA is predominantly IgG-mediated without complement deposition, yielding a positive anti-IgG DAT only.

Question 5

Which cytokine is the primary inducer of acute-phase protein synthesis in the liver?

Accepted Answer

IL-6

Answer

IL-6 is the principal cytokine that stimulates hepatocytes to produce acute-phase proteins such as CRP and fibrinogen.

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