The role of selectins and CD18 in leukotriene B4-mediated white blood cell emigration in human skin grafts transplanted on SCID mice.

The purpose of this study was to examine the role of selectins and CD18 cell adhesion molecules (CAMs) in inflammation induced by injection of leukotriene B4 (LTB4) into human skin. To accomplish this, the expression of CAMs and the ability of specific antibodies against CAMs to block white blood cell (WBC) transmigration were studied in an in vivo model consisting of human skin transplanted onto mice with the severe combined immune deficiency (SCID) mutation. The results indicate that LTB4-induced WBC transmigration in the human/SCID model is rapid and pronounced; however, it is not accompanied by a significant upregulation of the baseline expression of endothelial P-selectin, E-selectin, ICAM-1 or VCAM-1. An anti-murine CD18 mAb markedly inhibited white cell infiltration (89% inhibition) confirming the importance of beta 2 integrins in the process. The role of selectins was also examined. MEL-14, a bioactive antibody against murine L-selectin inhibited transmigration by 66%. A significant, but smaller, effect (39% inhibition) was observed by blocking E-selectin function. These results indicate that LTB4-induced inflammation does not require upregulation of endothelial CAM expression and, in contrast to TNF alpha-induced transmigration, is only partially blocked by anti-E-selectin antibodies.