các tế bào nội mô, hầu hết các tế bào lympho, và hầu hết các tế bào khác sau khi tiếp xúc với các cytokine tiền viêm như interleukin-1 (IL-1) hoặc khối u hoại tử yếu tố một (TNFa) ICAM1 liên kết LFA-1 và Mac-1 qua miền globulin miễn dịch đầu tiên và thứ ba của nó, tương ứng. ICAM-2 bao gồm hai lĩnh vực globulin miễn dịch và được thể hiện trên nghỉ ngơi tế bào nội mô cầu và tiểu cầu. | 324 Part I Basic Science endothelial cells most lymphocytes and most other cells after exposure to proinflammatory cytokines such as interleukin-1 IL-1 or tumor necrosis factor-a TNFa . ICAM-1 binds LFA-1 and Mac-1 through its first and third immunoglobulin domain respectively. ICAM-2 contains two immunoglobulin domains and is expressed on resting endothelial cells and platelets. It also binds LFA-1 and Mac-1. Vascular cell adhesion molecule-1 VCAM-1 is the main endothelial ligand for VLA-4 and is also expressed on inflamed smooth and cardiac muscle cells. Another class of immunoglobulins is engaged in homophilic interactions. Platelet-endothelial adhesion molecule-1 PECAM-1 is a six-domain immunoglobulin expressed by endothelial cells where it localizes to inter-endothelial borders and on platelets and most leukocytes. Antibodies to PECAM-1 inhibit monocyte and leukocyte transendothelial migration but PECAM-1 knockout mice show a clear defect in transendothelial migration only on some backgrounds. The junctional adhesion molecule JAM family encompasses three members JAM1 JAM2 and JAM3 that also localize to interendothelial borders and regulate endothelial monolayer permeability. In addition JAM1 interacts with LFA-1 JAM2 also called JAM-3 with Mac-1 and JAM3 also called JAM-2 with VLA-4. The JAMs are likely involved in regulating transendothelial migration. Physiology of Leukocyte-Endothelial Interactions In postcapillary venules leukocytes endothelial cells shear forces and adhesion molecules interact to allow leukocyte recruitment to sites of inflammation and lymphocyte recruitment to secondary lymphatic organs. The physiological processes discussed next have been observed in many model tissues and probably apply to skeletal muscle cardiac muscle skin and lymph nodes but not to the liver spleen or lung. In these latter organs the physiology of leukocyte recruitment is not well understood. Capture or Tethering Leukocyte adhesion is initiated by .
