BIOL 2050U Lecture Notes - Germinal Center, Immunoglobulin Class Switching, Chemokine
Document Summary
Lymphoid organs highly localized microenvironments are structural basis of immune response lymphocyte specificity is quite rare, as is their dispersement throughout the body soln: highly orchestrated movements of antigen. Primary lymphoid tissue bone marrow and thymus antigen recognition development positive/negative selection signaling apparatus in response to antigenic stimulation capacity to home to proper microenvironment. C-kit and stem cell factor interact on b-cell surface for lymphopoesis cell-cell contact w/ stromal cells also directs lymphopoesis. Capsule = lining; invaginates to form lobes lined w/ early t-cell progenitors. Cortical epithelial cells dendridic cells, stimulate t-cell maturation. Interdigitating cells boundary between cortex and medulla also called thymic dendridic cells bone-marrow derived. Localization of t-cell development- progenitors enter via capsule first replicate then undergo gene rearrangments. Cd4+/cd8+ developed that also have productive a/b tcr recombination. Cortical thymocytes then associate with epithelial cells positive sel. Cd4+ or cd8+ singly positive cells can proceed based on. **still unclear as to whether positive or negative selection occurs first**
