ATI RN
Immune System Exam Questions Questions
Question 1 of 5
An important effector function of antibodies is opsonization. Opsonized antigen can bind to Fc receptors on for instance macrophages. Which part of the antibody binds to the Fc receptor?
Correct Answer: C
Rationale: The Fc region (tail of heavy chains, C) binds Fc receptors on macrophages; Fab and antigen-binding parts bind antigens.
Question 2 of 5
What cytokine does a Th1 cell produce that influences B cells during class switching to produce IgG3?
Correct Answer: C
Rationale: IFN-γ from Th1 cells drives IgG3 class switching ; IL-4 favors IgE, TNF and IL-2 have other roles.
Question 3 of 5
How do NK cells recognize healthy cells?
Correct Answer: B
Rationale: NK cells spare healthy cells with MHC I ; opsonization is phagocytic, editing/selection (C, D) are lymphocyte processes.
Question 4 of 5
Substances called the are capable of directly inhibiting DNA synthesis
Correct Answer: B
Rationale: Interferons inhibit viral DNA/RNA synthesis; antibodies , complement , and histamines have other roles.
Question 5 of 5
The formation of the C3 convertase is a key step in complement activation that occurs in all three complement pathways. This enzyme cleaves C3 in blood plasma, leading to a conformational change in the C3b fragment that exposes its reactive thioester group. The activated C3b is potentially harmful to the host, if it becomes covalently attached to a host cell, rather than to the surface of a pathogen. This deleterious outcome is largely avoided by:
Correct Answer: C
Rationale: C3b hydrolyzes quickly in solution , preventing host damage; it can diffuse , attach to host cells , or bind convertase but is regulated.