Which of the following bind to mast cells and cross-link, resulting in degranulation and release of histamine?

Correct Answer: C

Rationale: IgE binds mast cells for histamine release; IgM , IgA , IgG , and interleukins don't.

Correct Answer: B

Rationale: Haptens are non-immunogenic alone, needing carriers; not inherently immunogenic .

Correct Answer: A

Rationale: The early development of stem cell takes place in primitive tissue, late development in fetal liver and final development in bone marrow, making bone marrow the primary site.

Correct Answer: D

Rationale: Defensins are peptide antibiotics in neutrophil granules, killing microbes directly, not oxygen-dependent enzymes.

Correct Answer: B

Rationale: Vaccination uses attenuated agents to induce immunity, preventing severe disease, unlike virulent strains or antibiotics.