ENDOTHELIAL-CELLS EXPRESSING AN INFLAMMATORY PHENOTYPE ARE LYSED BY SUPERANTIGEN-TARGETED CYTOTOXIC T-CELLS

The objective of this study was to investigate whether the superantige n staphylococcal enterotoxin A (SEA), which binds to HLA class II and T-cell receptor V beta chains, can direct cytotoxic T cells to lyse cy tokine-stimulated endothelial cells (EC). In addition, we wanted to de termine whether SEA-primed cytotoxic T cells could be targeted to EC s urface molecules as a means of a novel cancer immunotherapy. Human umb ilical vein EC (HUVEC), dermal microvascular EC (HMVEC), or the EC lin e EA.hy926 stimulated with gamma interferon (IFN-gamma) or tumor necro sis factor alpha (TNF-alpha) displayed upregulated HLA class II and ad hesion molecule (CD54 and CD106) expression, respectively. SEA-primed T cells induced a strong cytotoxicity against IFN-gamma- and TNF-alpha -activated EA.hy926 which had been preincubated with SEA. Blocking of CD54 completely abrogated the T-cell attack. SEA-D227A, which has a mu tated class II binding site, did not promote any cytotoxicity. A stron g lysis was observed when a fusion protein consisting of protein A and SEA-D227A was added together with T cells to TNF-alpha-induced EA.hy9 26 and HUVEC precoated with monoclonal antibodies (MAb) directed again st HLA class I, CD54, or CD106 molecules. Finally, an scFv antibody fr agment reactive with an unknown EC antigen was fused with SEA-D227A. B oth EA.hy926 and HMVEC were efficiently lysed by scFv-SEA-D227A-trigge red cytotoxic T cells. Taken together, superantigen-activated T-cell-d ependent EC killing was induced when EC expressed an inflammatory phen otype. Moreover, specific MAb targeting of the superantigen to surface antigens induced EC lysis. Our data suggest that directed T-cell-medi ated lysis of unwanted proliferating EC, such as those in the tumor mi crovasculature, can be clinically useful.