1、Chapter 15 Leukocyte Migration and Inflammation,The IS relies upon the continual circulation of leukocytes through the body For the Innate IR a variety of lymphocytes, granulocytes, and monocytes can respondFor the Adaptive IR lymphocytes must contact Ag in either tissue, lymph, or blood,Lymphocyte
2、re-circulation,Lymphocytes constantly re-circulate from blood to spleen, lymph nodes, and 3 lymphoid tissues Continual circulation provides systemic protection A complete circuit can be performed 1-2X per day 1 in 105 lymphocytes can recognize a specific Agtherefore, constant circulation increases c
3、hance of lympho contacting Ag,How do leukocytes transit the bloodstream?,They must bind to an endothelial cell first!Endothelial cells exhibit cell adhesion molecules CAMsLymphos, granulos, and monos form receptors which bind to CAMs,The four types of CAMs,Selectins resp. for intial contact between
4、leukocytes and endothelial cells Bind to specific CHO groups (i.e., mucins) Mucins glycosylated proteins Bind to selectins on endothelium Bind to other mucins (CD34 and glyCAM) on endothelium of lymph nodes,The four types of CAMs,Integrins heterodimer proteins formed by all leukocytes Bind to ICAMs
5、along vasc. endotheliumICAMs CAMs with Ig domains on vasc. endothelia Bind to integrins at Ig domain MadCAMs have both IG and mucin-like domains; found on mucosal endothelia Bind to integrins on lymphocytes,Neutrophil extravasation in inflammation,Blood flow,Cell adhesions of neutrophils,Rolling,Act
6、ivation,Adhesion,Lymphocyte extravasation,Involves same 4 steps as neutrophilsSmall % of endothelial cells w/i lymphoid organs exhibit “high-endothelial venules” (HEVs) which contain many CAMsCAMs function in “Homing” and “Trafficking” of lymphocytes,Initial contact of Nave lymphocytes,High endothelial venule cell,Steps of extravasation of nave T cell,Initial contacts of effector T cells,
