title: Monoclonal antibody anti-NC-2 identifies a second receptor on cells mediating natural cytotoxicity in mice.
abstract: We have previously reported the identification by the murine monoclonal antibody (mAb) 1C4 of the first leucocyte receptor which is involved in natural cytotoxicity (NC) against WEHI-164; the NC-1.1 receptor. We report herein the identification and characterization of a second leucocyte receptor which is involved in NC, NC-2 (MW 50,000), identified by a rat anti-mouse mAb D9 (immunoglobulin G2a; IgG2a). Flow cytometric analysis showed that NC-2 was expressed on < 6% of splenic leucocytes of different inbred mouse strains and 96% of the cells of a mast-cell line which has high NC activity. In vitro treatment of splenic leucocytes with the D9 mAb blocked effector cell-WEHI-164 target cell conjugation and NC by approximately 50% without affecting natural killing (NK). Western blot analysis of affinity purified NC-2 and NC-1.1 using the D9 and 1C4 mAbs showed specific reactivity of the proteins with D9 and 1C4, respectively. Pretreatment of splenic leucocytes with both mAbs blocked NC 84%, a result which almost doubled that caused by either mAb alone. Flow cytometric screening of 16 different mouse cell lines showed that 19% of the cell lines expressed both receptors, 6% expressed only NC-2, 44% expressed mainly or only NC-1.1 and the remaining cells expressed neither receptor. These data indicate that D9 identifies a xeno-antigen, NC-2, which is expressed on cells mediating NC and not NK, and that it is not the previously described NC-1.1 allo-antigen. We conclude that NC-2 is likely to be one of a number of receptor molecules on cells mediating NC against tumour cells.
authors.affiliation: Faculty of Medicine and Health Sciences, University of Newcastle, Australia.
authors.forename: H
authors.initials: H
authors.lastname: Shirzadeh
authors.forename: R C
authors.initials: RC
authors.lastname: Burton
authors.forename: J H
authors.initials: JH
authors.lastname: Brien
authors.forename: Y C
authors.initials: YC
authors.lastname: Smart
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D002469:Cell Separation; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D007962:Leukocytes / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D011956:Receptors, Cell Surface / Q000032:analysis* / Q000276:immunology; D013154:Spleen / Q000276:immunology; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D011956:Receptors, Cell Surface