title: Mapping functional epitopes of the human LFA-1 glycoprotein: monoclonal antibody inhibition of NK and CTL effectors.
abstract: Anti-LFA-1 monoclonal antibody (MoAb) was originally identified by screening antibodies for their ability to inhibit cytolysis in the absence of complement. Anti-LFA-1 MoAb has been shown to inhibit both natural killer (NK) and cytolytic T lymphocyte (CTL) mediated cytolysis. To further define the utilization of this molecule in cell-mediated cytolysis, we used a panel of MoAb to functional epitopes on both the alpha and beta chains of the LFA-1 heterodimer. The panel was used to compare OKT3- NK effectors and OKT3+ CTL clones. As expected, function-associated MoAb to CTL antigens (T3, T8, LFA-2) and target cell antigens (HLA, LFA-3) blocked only CTL clones and not NK effectors. In contrast, anti-LFA-1 MoAb blocked both NK effectors and CTL clones. In addition, the panel of anti-LFA-1 MoAb demonstrated an identical hierarchy of functionally relevant LFA-1 epitopes. Given the similar utilization of LFA-1 in NK and CTL mediated cytotoxicity assays, we explored the ability of MoAb to different epitopes on LFA-1 to inhibit conjugate formation. Anti-LFA-1 MoAb inhibition of NK-target binding paralleled the inhibition of CTL-target binding. Thus, functional epitopes on the LFA-1 molecule have been defined for NK and CTL effectors. The identical hierarchy of functional epitopes indicates that the LFA-1 molecule is similarly utilized in NK and CTL mediated cytotoxicity and that the relevant epitopes are involved in effector-target conjugate formation.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000627:therapeutic use; D000954:Antigens, Surface / Q000037:antagonists & inhibitors / Q000276:immunology*; D002450:Cell Communication / Q000187:drug effects; D003601:Cytotoxicity Tests, Immunologic; D000939:Epitopes / Q000032:analysis*; D006801:Humans; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology*; D007942:Leukemia, Experimental / Q000276:immunology; D007951:Leukemia, Myeloid / Q000276:immunology; D016169:Lymphocyte Function-Associated Antigen-1; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000187:drug effects / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D000939:Epitopes; D016169:Lymphocyte Function-Associated Antigen-1