title: General considerations in the interpretation of I-J genetic restrictions: evidence that the antigen-binding chain of antigen-specific T-suppressor factor has two recognition sites for members of the I-J hierarchy.
abstract: (CBA X B10)F1 [(H-2k X H-2b)] mice produce two types of antigen-specific T-suppressor factor (TsF), which can be separated by affinity chromatography on anti-I-J monoclonal antibody. After reduction and alkylation, both chains of F1 TsF are required for biological activity. However, the antigen-binding chain (AgBC) of F1 TgFk (AgBCk) is only complemented by I-Jk and likewise for F1 TsFb. In other words, interchain complementation shows the same genetic restriction in interchain complementation in parental and F1 mice. F1 TsF bearing, for example, I-Jk (TsFk), interacts with haptenized 'antigen-presenting cells' ('APC') and parental I-Jk chains interacts with haptenized 'APC' of both parental haplotypes (dual reactivity). In contrast, the combination of parental AgBCb and F1 I-Jb shows single reactivity and only interacts with haptenized 'APCb'. It was inferred that the antigen-binding chain is responsible for the dual reactivity and, hence, for the interaction with a member of the I-J hierarchy on the 'APC'. It was concluded that the antigen-binding chain of TsF has two recognition sites for members of the I-J hierarchy--one for interchain complementation and the other for interaction with the haptenized 'antigen-presenting cell'. The term member of the I-J hierarchy is used instead of I-J because it is not clear whether the AgBC interacts with I-J or a receptor for I-J, or indeed a receptor for that receptor.
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D001665:Binding Sites; D003433:Crosses, Genetic; D000939:Epitopes / Q000235:genetics* / Q000276:immunology; D005816:Genetic Complementation Test; D006239:Haplotypes; D000949:Histocompatibility Antigens Class II / Q000235:genetics* / Q000276:immunology; D051379:Mice; D008954:Models, Biological; D013045:Species Specificity; D013329:Structure-Activity Relationship; D013491:Suppressor Factors, Immunologic / Q000235:genetics* / Q000276:immunology
chemical_list: D000939:Epitopes; D000949:Histocompatibility Antigens Class II; C043911:I-J-antigen; D013491:Suppressor Factors, Immunologic