Antibody 12-15 cross-reacts with mouse Fc gamma receptors and CD2: study of thymus expression, genetic polymorphism and biosynthesis of the CD2 protein.
Previously we described a monoclonal antibody (mAb 12-15) that reacted with murine Fc receptor proteins (beta 1, beta 2 and alpha) and an undefined molecule of 37 kDa (beta 3) on certain types of cells. Here we present serological and biochemical evidence that the beta 3 chain is expressed on mouse thymocytes and that it is identical to the CD2 antigen. By immunofluorescence staining and cytofluorographic analysis greater than 95% of thymocytes were positive. Brightly staining cells coincided with cortisone-resistant thymocytes suggesting that mature thymocytes expressed higher levels of the antigen. Biosynthetic labeling of DBA/2 thymocytes with [35S]methionine showed that the size of the CD2 precursor molecule was 43 kDa which was processed to approximately 55-65 kDa in the mature molecule. mAb 12-15 was also reactive with the tunicamycin-treated form of the CD2 antigen suggesting that the cross-reactive epitope was of protein nature. Comparison of different mouse strains indicated that two molecular forms of CD2 exist. On BALB/c thymocytes, the relative mass of the native molecule was approximately 60-70 kDa (CD2.1) and slightly larger than in DBA/2 (CD2.2). Following endoglycosidase F treatment both proteins still showed a slight difference in electrophoretic mobility. Several inbred mouse strains were analyzed for expression of CD2 forms. When mAb 12-15 was used in cytotoxic T lymphocyte inhibition experiments using specific CTL and tumor target cells it was found that the antibody could specifically inhibit CTL-mediated lysis presumably by interfering with CD2 function.
Altevogt
P
P
Institut für Immunologie und Genetik, DKFZ, Heidelberg, FRG.
Kohl
U
U
Von Hoegen
P
P
Lang
E
E
Schirrmacher
V
V
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000502:physiology; D000943:Antigens, Differentiation / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D001667:Binding, Competitive; D018801:CD2 Antigens; D003429:Cross Reactions; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D051379:Mice; D008807:Mice, Inbred BALB C; D008811:Mice, Inbred DBA; D011110:Polymorphism, Genetic; D011961:Receptors, Fc / Q000276:immunology*; D017452:Receptors, IgG; D011971:Receptors, Immunologic / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D013950:Thymus Gland / Q000032:analysis*
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D000945:Antigens, Differentiation, T-Lymphocyte; D018801:CD2 Antigens; D008565:Membrane Proteins; D011961:Receptors, Fc; D017452:Receptors, IgG; D011971:Receptors, Immunologic