title: The structure-function relationship of I-A molecules: correlation of serologic and functional phenotypes of four I-Ak mutant cell lines.
abstract: We have isolated and characterized four mutant I-Ak-expressing cell lines derived from the B cell-B lymphoma hybrid antigen-presenting cell line TA3. The mutants were isolated by first selecting against expression of one Ak epitope by treatment with a monoclonal antibody in the presence of complement and then selecting for retention of a second Ak epitope by electronic cell-sorting of cells stained for fluorescence with a second monoclonal antibody. The serologic and functional phenotypes of the mutants were characterized by using panels of I-Ak-specific monoclonal antibodies and I-Ak-restricted T hybridomas. We obtained one Ak alpha mutant (J4) that no longer reacts with any Ak alpha-specific antibody and also is incapable of stimulating any I-Ak-restricted T hybridoma. We obtained three Ak beta mutants (LD3, K5, G1) that express a wide range of serologic and functional phenotypes. Correlation of the serologic and functional phenotypes reveals that the serologic epitope Ia.1 may overlap with a major site of T cell recognition, whereas the Ia.17 serologic epitope appears to be only a minor site for T cell recognition.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000938:Antigen-Presenting Cells / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D002460:Cell Line; D002469:Cell Separation / Q000379:methods*; D000949:Histocompatibility Antigens Class II / Q000235:genetics* / Q000276:immunology; D008223:Lymphoma / Q000235:genetics / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D010641:Phenotype; D013329:Structure-Activity Relationship; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II