ATI RN
Immune System Quiz Questions Questions
Question 1 of 5
What is the function of CTLA-4 on T cells?
Correct Answer: B
Rationale: CTLA-4 inhibits T-cell activation by competing with CD28 ; it doesn't activate (A, C) or target B7 directly .
Question 2 of 5
The antigen receptor on a T cell recognizes a degraded fragment of a protein (i.e., a peptide) bound to a specialized cell surface peptide-binding receptor called an MHC molecule. One key aspect of this system is that the peptides displayed on MHC molecules can be derived from intracellular proteins. This mode of antigen recognition is particularly important in allowing the adaptive immune response to detect infections by:
Correct Answer: B
Rationale: MHC presentation of intracellular peptides detects viruses/protozoa ; extracellular pathogens (C, D) or helminths are less MHC-dependent.
Question 3 of 5
Macrophages express multiple types of receptors on their surface that stimulate phagocytosis of microbes, leading to pathogen internalization and destruction. Many of these receptors, such as Dectin-1, rely on direct recognition of a PAMP on the pathogen surface. However, some receptors that stimulate phagocytosis rely on soluble factors (not associated with the phagocyte membrane) to identify and mark the pathogen for uptake by the phagocyte. One such receptor is:
Correct Answer: D
Rationale: Complement receptors bind soluble C3b; mannose , scavenger , and lectin receptors bind PAMPs directly.
Question 4 of 5
In rare instances, B cells can be found that have two immunoglobulin light chain alleles, both of which are rearranged in frame, and can encode functional light chain proteins. Yet, on the surface of the B cell, only one of the two light chain proteins is detected in the membrane-bound immunoglobulin receptor. The reason these rare cells have two functional light chain rearrangements but only express one of the two light chains as part of the B-cell receptor is:
Correct Answer: B
Rationale: Allelic exclusion ensures one light chain pairs with heavy chain ; pseudogenes , transcription , or RAG don't explain this.
Question 5 of 5
the characteristic of blood types AB is
Correct Answer: A
Rationale: Blood type AB is a universal recipient (general receptor) because it has no antibodies against A, B, or Rh antigens, but it is not a universal donor.