ABSTRACT
Tissue infiltration by leukocytes is the pathological substrate of many chronic inflammatory and (jlltoimmune diseases, including vasculitis. The development of inflammatory infiltrates in tissues requires dynamic and precisely regulated interactions among leukocytes, endothelial cells, and the underlying basement membrane and interstitial matrix (1). Such interactions are mediated by a complex array of leukocyte surface receptors and their ligands on the endothelial cell membrane. On the leukocyte surface, carbohydrates closely related to sialylated forms of Lewisx and Lewisa antigens, selectins, and integrins interact in a sequential and precisely regulated manner with specific counterreceptors on the endothelial cell surface. Again, these include carbohydratebearing mucins, selectins, and immunoglobulin superfamily members. The main molecules involved in the interactions among leukocytes, endothelial cells, and extracellular matrix proteins are summarized in Table 1. Descriptions of their structural as well as functional properties have been addressed in detail in recent, comprehensive reviews (1-6).
