Human lymphocyte function-associated antigen (LFA)-1, a heterodimeric lymphocyte surface glycoprotein of 177,000 and 95,000 relative molecular weight has been implicated to function in the cytotoxic T lymphocyte (CTL) effector mechanism. Seven mouse hybridoma lines producing monoclonal antibodies (MAb) reactive with this structure were studied. Three unique and 3 partially overlapping epitopes on human LFA-1 were defined by competitive cross inhibition binding assays using biosynthetically labeled anti-LFA-1 MAb. In contrast, of five rat anti-mouse LFA-1 MAb, all five recognized a common or shared epitope. An HLA-B7 specific human CTL line expressed 1.1 x 105 LFA-1 sites per cell with a direct saturation binding assay. Human CTL expressed two to four times more LFA-1 than peripheral blood lymphocytes or B and T lymphoblastoid cell lines. Titration of each of the anti-LFA-1 MAb in a 51chromium release cytolytic assay revealed quantitative differences in the ability of the different anti-LFA-1 MAb to block cytolysis indicating distinct functional and antigenic epitopes exist on the human LFA-1 molecule. Anti-LFA-1 MAb reversibly inhibited the CTL reaction by slowing the initial rate of cytolysis. These results suggest anti-LFA-1 MAb inhibit CTL function by specific blockade of a functionally relevant molecule.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Immunology|
|State||Published - Oct 13 1983|
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