Three distinct antigens associated with human T-lymphocyte-mediated cytolysis: LFA-1, LFA-2, and LFA-3.

TLDR

LFA‑1 is a heterodimeric antigen (~272 kDa) expressed on B and T lymphocytes, marking subpopulations and homologous to the mouse protein, and is also present on cytotoxic T lymphocyte lines. Monoclonal antibodies against HLA‑DR CTLs were produced and screened for inhibition of CTL killing, while the antigens were characterized by immunoprecipitation, crosslinking, SDS‑PAGE, and flow‑cytometric immunofluorescence. Antibody binding to LFA‑1, LFA‑2, LFA‑3, and HLA‑DR inhibited CTL‑mediated killing, indicating their participation in CTL.

Abstract

Monoclonal antibodies were prepared to anti-HLA-DR cytolytic T lymphocytes (CTLs) and screened for inhibition of CTL-mediated killing. Binding of monoclonal antibodies to four types of molecules, LFA-1, LFA-2, LFA-3, and HLA-DR, inhibited killing, suggesting that these molecules participate in the CTL-target cell interaction. The antigens were characterized by immunoprecipitation, crosslinking, NaDodSO4/polyacrylamide gel electrophoresis, and immunofluorescence flow cytometry. The LFA-1 antigen contains alpha and beta polypeptide chains of Mr 177,000 and 95,000 that are noncovalently associated in an alpha 1 beta 1 structure. It is present on both B and T lymphocytes and marks subpopulations that differ in quantitative expression. Human LFA-1 appears to be the homologue of mouse LFA-1. Human LFA-2 is of Mr 49,000 with a minor component of Mr 36,000. It is expressed on CTL lines but not on a B-cell line and in peripheral blood preferentially on T lymphocytes. Human LFA-3 is of Mr 60,000 and is expressed on both B and T lymphocytes.