Superantigens but not mitogens are capable of inducing upregulation of E-selectin ligands on human T lymphocytes.

Bacterial infections can exacerbate immune mediated dermatoses, possibly via superantigens produced by these bacteria. Therefore, we asked whether superantigens induce the expression of adhesion molecules which may then facilitate invasion of highly activated T cells into different organs. The influence of exfoliative toxin (ET) and toxic shock syndrome toxin-1 (TSST-1) stimulation on the expression of a broad panel of adhesion and costimulatory molecules was investigated by flow cytometry. We found that only the E-selectin ligands cutaneous lymphocyte-associated antigen (CLA) and sialylated Lewis(x) (CD15s) are significantly upregulated by these superantigens but not by mitogen stimulation. In contrast, the mucosal lymphocyte-associated antigen (MLA) recognized by the monoclonal antibody Ber-Act8 was not differentially induced by mitogen or superantigen stimulation. Therefore, T lymphocyte stimulation by bacterial superantigens might directly influence their skin homing capacity. Furthermore, the superantigen-driven induction of CD15s-an adhesion molecule which is absent or only weakly expressed by resting or mitogen stimulated T cells-may indicate a role of this antigen for T cell skin homing. An additional adhesion pathway via E-selectin may thus be available to lymphocytes, comparable to granulocytes which constitutively express CD15s.