Vβ-restricted T cell adherence to endothelial cells -: A mechanism for superantigen-dependent vascular injury

Objective. To investigate the potential for endothelial cells to operate as superantigen-presenting cells for T cells and the potential for such an interaction to cause endothelial cell activation and injury. Methods. Class II major histocompatibility complex (MHC)-positive human umbilical vein endothelial cells (HUVECs) were cocultured for 4 hours with purified T cells and the superantigens staphylococcal enterotoxin B (SEB) or toxic shock syndrome toxin 1 (TSST-1). After staining with fluorescence-conjugated monoclonal antibodies, flow cytometric analysis was performed on the HUVECs and T cells to examine V-beta-restricted T cell adherence to the endothelial cell monolayer, V-beta-restricted T cell activation (CD69 up-regulation), surface expression of endothelial cell activation markers, and generation of endothelial microparticles (EMPs). Results. Coculture of purified T cells with class II MHC-positive HUVECs and either TSST-1 or SEB resulted in V-beta-restricted CD69 up-regulation by CD4 and CD8 cells (V(beta)2 activation for TSST-1; V(beta)3 V(beta)5.1, and V(beta)12 activation for SEB). Additionally, there was CD4 and CD8 T cell V-beta-restricted adherence to the HUVEC monolayer at 4 hours. Expression of intercellular adhesion molecule 1, E-selectin, and vascular cell adhesion molecule 1 was up-regulated on the class II MHC-positive HUVECs following exposure to superantigen in the presence of T cells, and there was increased EMP release from activated HUVECs, which occurred earlier and was of greater magnitude than that observed in response to tumor necrosis factor alpha. Conclusion. Class II MHC-positive endothelial cells operate as competent superantigen-presenting cells for CD4 and CD8 lymphocytes in vitro. Dual signaling between endothelial cells and T cells results in V-beta-restricted activation and adherence to endothelial monolayers and endothelial cell activation and release of EMPs expressing inducible cell adhesion molecules. It is proposed that this mechanism could account in part for the vascular injury associated with superantigen-mediated diseases including Kawasaki disease.