Th1 cell-mediated resistance to cutaneous infection with Leishmania major is independent of P- and E-selectins

Studies in several models of inflammation have underscored the importance of P- and E-selectins in the migration of T cells to inflamed tissues. However, the role of the endothelial selectins in infection-induced cutaneous inflammation and host-protective immunity has not been investigated. In this study, we demonstrate that CD4(+) T cells recruited to the cutaneous compartment during infection with Leishmania major express P- and E-selectin ligands. Furthermore, expression of P- and E-selectin ligands correlates with activated Leishmania-specific Th1 cells and is dependent upon IL-12. To investigate the functional role of the endothelial selectins during leishmaniasis, we infected mice either singly or doubly deficient in the expression of P- and E- selectins. Mice lacking both P- and E-selectins developed significantly less inflammation at the site of a primary and secondary infection, and exhibited an impaired delayed-type hypersensitivity response. Surprisingly, the absence of the endothelial selectins had no effect on the control of parasite replication or immunity to reinfection. Thus, these data demonstrate that although the endothelial selectins contribute to the inflammatory response, they are not required for protective immunity to L. major. Moreover, these data suggest that by blocking P- and E-selectins, the immune pathology associated with cutaneous leishmaniasis might be ameliorated without compromising immunity to infection.