title: p150/95, Third member of the LFA-1/CR3 polypeptide family identified by anti-Leu M5 monoclonal antibody.
abstract: Monoclonal antibody (mAb) anti-Leu M5 reacts with a two-chain molecule composed of a 150-kDa alpha subunit noncovalently associated with a 95-kDa beta subunit and probably is specific for an epitope on the 150-kDa alpha chain. This p150/95 antigen is the third member of a family of polypeptides sharing a common 95-kDa beta chain, which includes the lymphocyte function-associated antigen LFA-1 (p177/95) and complement receptor CR3 (Mo1/MAC-1/OKM1; p165/95) antigens. Sequential immunoprecipitation with anti-p95 beta chain mAb specifically removed the antigens detected by anti-LFA-1, anti-CR3 and anti-Leu M5 mAb. Certain patients with recurrent bacterial infections are genetically deficient in expression of the LFA-1 and Mo1 antigens, and have impaired granulocyte function. Granulocytes from a patient with this disease also failed to react with anti-Leu M5. Stimulation of normal granulocytes with f-Met-Leu-Phe, C5a-desArg, or calcium ionophore resulted in increased expression of Mo1 and Leu M5 antigens on the cell surface, but did not significantly increase expression of LFA-1 antigen. In functional assays, anti-Leu M5 did not inhibit T cell-mediated or natural killer cell-mediated cytotoxicity. In addition, anti-Leu M5 neither inhibited the binding of complement-coated particles to CR1 or CR3 nor did it affect the binding of EC3dg to neutrophils (CR4). These studies clearly indicate that the p150/95 antigen recognized by the anti-Leu M5 antibody is a structurally distinct member of the LFA-1/CR3 family.
mesh_terms: D000911:Antibodies, Monoclonal / Q000502:physiology; D000937:Antigen-Antibody Reactions; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis* / Q000276:immunology*; D001667:Binding, Competitive; D003602:Cytotoxicity, Immunologic; D006098:Granulocytes / Q000276:immunology; D006801:Humans; D016169:Lymphocyte Function-Associated Antigen-1; D010455:Peptides / Q000032:analysis* / Q000276:immunology; D010585:Phagocyte Bactericidal Dysfunction / Q000276:immunology; D011233:Precipitin Tests; D012008:Recurrence
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D016169:Lymphocyte Function-Associated Antigen-1; D010455:Peptides