Question

1. Which of the following statements is (are) true of a T cell that expresses two α chains (and thus two different T-cell receptors) as a result of ineffective allelic exclusion of the α chain during rearrangement?

   1. There will be two unique TCRs on the surface of this T cell.

   2. Engaging either of the T-cell receptors on MHC molecules of the thymic epithelium will result in positive selection.

   3. If either T-cell receptor binds strongly to self-peptide presented by self-MHC molecules, the thymocyte will be negatively selected.

   4. The T cell will require twice as many peptide-MHC molecules to elicit similar signaling compared to a normal T cell with one TCR.

   5. All of the above are true

2. Pro-B cells produce a surrogate light chain, which associates with the μ chain on the cell surface. The surrogate light chain is composed of:

   1. E2A and EFB.

   2. Igα and Igβ.

   3. VpreB and λ5.

   4. RAG-1 and RAG-2.

   5. Pax5 and CD19

3. Which of the following characterizes the B-1 cells that develop prenatally?

   1. They lack N nucleotides.

   2. They possess polyspecificity for bacterial polysaccharide antigens.

   3. They arise early in embryonic development preceding the development of the majority subset of B cells.

   4. They have little or no IgD on the cell surface.

   5. All of the above

4. The name given to a fully activated and differentiated B cell that secretes antibody is:

   1. T cell

   2. antigen-presenting cell

   3. hematopoietic cell

   4. secretory cell

   5. plasma cell

5. The antigen-binding site of an immunoglobulin is formed from:

   1. the V regions of light chains only

   2. the C regions of heavy chains only

   3. paired V regions of a single heavy chain and a single light chain

   4. paired V regions of two light chains

   5. paired C regions of two heavy chains

Answer 1

Answer for question 1. If either T-cell receptor binds strongly to self-peptide presented by self-MHC molecules, the thymocyte will be negatively selected. This is because it needs both alpha and beta to function

Answer for question 2 VpreB and λ5.

Answer for question 3. All if the above.

Answer for question 4 plasma cell