cell interactions

Outline of Lecture 18 Cell Interactions and Primary Immunodeficiency I. Primary Lymphoid Organs - Role: Produce clonally diverse lymphocytes with broad but tolerant Ag recognition A) Bone Marrow - Site of initial production of all hematopoietic cells - Stromal cells provides support and cytokines for hematopoiesis 1) B-lymphopoiesis - Full progression from stem cell to mature sIg+ B cell - Vectoral (precursors found at periphery whereas mature cells are in the center) - Important factors: IL-7, fibronectin, CD44/hyaluronate, integrins - B cell loss through bad rearrangements and negative selection (clearance through macrophages) 2) T-lymphopoiesis - CD7+ stem cell proceeds to pro-thymocyte, which travels to thymus B) Thymus (see diagram p. 315) - TCR rearrangement occurs in the cortex - Cortical epithelium cells mediate positive selection - Medullary epithelium cells and macrophages (also at CMJ) are negative selecting II. Secondary Lymphoid Tissues A) These tissues are: lymph node, spleen, mucosal associated lymphoid tissues B) Structure (know each): afferent lymph vessel, subcapsular sinus, cortex, paracortex (T zone), medulla, hilum, efferent lymph vessel, high endothelial vessel, follicle, germinal center C) DC’s enter through affere