BIO 546 IMMUNOLOGYThursday, March 11, 2004 ONLINE TESTEach multiple choice question has one answer unless indicated otherwise atthe end of the question1. If a fully mature autoreactive B-lymphocyte leaves the bone marrow andis not anergic, what will happen if that B-cell forms high affinity bondswith the self-antigen for which it is specific? (one answer)A. it will then become anergic, rendering it unable to respondB. it will die (by apoptosis)C. it will respondD.
it will cease to express B7 molecules2. Initiation of B-cell development eventually stimulates initiation ofgene fragment somatic recombination for heavy and light chains. Theserecombination events occur within the nucleus and are started when whichone of the following is activated?A. recombinant activation genes (RAG)B. Ig-alpha and Ig-beta trans nuclear membrane “tails”C. apoptosis-inducing nucleoside sequencesD.
B73. Elimination of autoreactive T-cytotoxic lymphocytes (“negative”selection) occurs when which one of the following conditions is met?A. high affinity bonds form between the T-cell antigen receptor and anantigen presented by an MHC Class IIB. at the same time that the T-cell becomes “restricted” with regard to theMHC Class I molecules that can successfully present peptides to theautoreactive T-cellC.
high affinity covalent bonds form between the T-cell antigen receptorand an antigen presented by a MHC Class ID. high affinity non-covalent bonds form between the T-cell antigenreceptor and an antigen presented by a MHC Class I4. Which one of the following types of cells is encountered first as a stemcell begins to move through the thymus during its development into a fullyfunctional T-cytotoxic cell?A. cortical epithelial cellsB. double-positive dendritic cellsC.
macrophages presenting very large numbers of peptides using MHC Class IID. stromal cells expressing Kit and SCF, and also secreting IL-75. The original source of the dendritic cells and macrophages that arefound in the medulla of the thymus is which one of the following?A.
the cortex of the thymus (the cells simply move inward to the medullaand prepare to participate in negative selection)B. the bone marrow (same area from which the stem cells originate that willeventually become T-cells)C. they are permanent residents of the thymus medulla (i.e., are “born”there) and remain in the medulla to participate in positive selectionD. the spleen (which is often an ignored organ when the immune system isstudied in detail)6. The cell that is most directly responsible for initiating B-celldevelopment and several of the early steps in that development is which oneof the following?A. dendritic cellB.
epithelial cell (in the cortex)C. endothelial cell expressing high levels of VCAM-1D. stromal cell7. There is a series of cell-cell interactions during B-cell developmentthat involve surface molecules of both the B-cell and the cell thatinitiates the development process.
Which one of the following is an exampleof one of those surface-surface interactions?A. IL-7 and IL-7 receptorB. Kit and SCFC.
MHC Class I and CD8D. heavy chain and surrogate light chain8. MHC restriction refers to a process that takes place during T-celldevelopment that ensures a proper “fit” between which TWO of the following?(select TWO answers that are correct)A. MHCB. the T-cell antigen receptorC.
CDD. CD289. The appearance of which one of the following on the surface of adeveloping B-lymphocyte indicates that a heavy chain has been successfullyproduced, but creation of a light chain has not begun?A. functional antigen receptors of the IgM isotype (monomeric form)B.
a non-functional receptor-like molecule (2 heavy chains and 2 surrogatelight chains)C. a non-functional receptor-like molecule (1 beta chain and 1 surrogatealpha chain)D. a non-functional receptor-like molecule with 2 complete, functional Fabportions10. Good cell adhesion is very important to cells that are interacting witheach other. Often the interactions between two surface molecules on twointeracting cells will alter other sets of interacting molecules and affectthe overall adhesion of the two cells. For example, when a T-cell receptorforms high affinity bonds with a peptide presented by an MHC and the CDmolecule also forms bonds with the same MHC, nearby LFA-1 and ICAM-1molecules are affected in which one of the following ways?A.
these two surface molecules form even stronger bondsB. the LFA-1 disappears, and is replaced by a much higher affinity IL-7receptorC. these two surface molecules dissociate, and the contact between the twocells ceases (as the cells have completed all of the necessary steps thatoccur during the adhesion phase)D. if the T-cell has