BIOL 2005 Lecture Notes - Ctla-4, Chemokine, T Helper Cell
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**