Which cell type secretes cytokines such as II, -7 and expresses surface receptors that signal bone marrow stem cells to differentials into monocytes, B cells, neutrophils, or T cell progenitors? Hematopoietic bone marrow stem cell Bone marrow stromal cells Thymic cortical epithelial cells Pluripotent bone marrow stem cell Dendritic cell In a mature B cell the combined rearrangement of VDJ segments in the gene locus for antibody heavy chain as well as the rearranged VJ segments m the gene locus for the light chain determines which of the follow? The DNA code for the class of antibody it can produce and if it can he secreted into body fluids to attack worms or bacteria The DNA code for the amino acid sequence that forms the binding specificity within the Fab region of its B cell receptors The DNA code for the constant ammo acid sequences in the carboxyl terminals of the polypeptide chains that make-up their antigen receptors all of the above answer choices are correct both answer choices b and c are correct The Fc portion of secreted antibodies is composed of which of the following? the amino terminal half of the two light chains and heavy chains the carboxyl terminal halves of the light chains and heavy chains the carboxyl terminal halves of the two heavy chains the part of the antibody that is changed by somatic hypermutations the amino terminal ballot the two heavy chains Which of the following provides each normal human the ability to produce over 5 times 10^13 different immature B cell antigen receptors and thus the same number of immature B cell clones? alternative splicing of pre-mRNA encoding immunoglobulin polypeptide chains DNA rearrangements in both the heavy chain locus and the light chain locus during B cell development somatic hyper mutations in B cell DNA genes encoding immunoglobulin chains DNA rearrangements in either the heavy chain locus or the light chain locus during B cell development crowing over between antibody light chain loci and heavy chain loci during meiosis 1 Which of the following causes most of the immature B cells produced during development in the bone marrow to die of apoptosis? They express self-reading co-receptors of B-cells They express B-cell receptors that bind strongly lo self-antigens expressed on bone marrow Stromal cells They express B-cell receptors that hind weakly to self-antigens expressed on bone marrow Stromal cells They express self-reading B7 (CD 80/86) receptors All of the above answer choices are correct Which of the following processes is used by plasma cells lo antibodies rather than producing cell surface bound B cell receptors? Somatic recombination of the DNA genes coding tor the heavy chains Somatic by permutation of the genes coding tor immunoglobulin chains Alternative splicing of the pre-mRNA encoding the immunoglobulin heavy chains al the sue that code for the hydrophobic amino acid sequence near the carboxyl end heavy chains Isotype switching in the DNA genes that encode the immunoglobulin heavy chains Alternative splicing together of DNA V segments, D segments, and J segments in the genes that encode the immunoglobulin heavy chains. the following phases of a B cell’s life history in order by matching the following answer choices with the next questions: Circulating between blood and lymphoid tissues until its B cell receptors can bind strongly specific antigen secondary lymphoid tissue.