BIOL 1010U Lecture Notes - Immunoglobulin Class Switching, Clonal Deletion, Thymus
Document Summary
Phases of b cell development prenatal in liver postnatal bone marrow from hematopoetic stem cells. Allelic exclusion only one allele is expressed higher specificity a result of ordered gene rearrangement: clp common lymphoid progenitor, prob dj rearr. (hc) stim by b220 (cell surface antigen) occurs on both alleles. Detecting b cell developmental state: anti b220 stains for b cell lineage anti cd43 stains for maturation. Cd43 anchors prob cells to marrow no cd43, but b220 present preb cell. Regulation of ig gene rearr. txn of rag genes activity of vdj recombinases. **susceptibility of loci to recombination** accessibility hypothesis euchromatin necessary during active rearrangement. Rag deficient mice are stuck in prob state (cd43+, b220+) add hg protein advance to preb state. Hc present on surface with invariant surrogate lc"s (vpreb and lambda-5) Lc"s escort hc to cell surface and are necessary for prebcr exposure and. Thus necessary for b-cell development lambda knockouts have no b-cells.
