Competition among class II major histocompatibility molecules for presentation of tyrosine-azobenzenearsonate occurs in vivo and in vitro.
We have compared by functional assays the relative preference among Ia molecules for their ability to present tyrosine-azobenzenearsonate (ABA-Tyr) to T cells. Immunization of B10.BR mice (IAk, IEk) with ABA-Tyr resulted in the induction of IAk-restricted T cells only. Immunization of B10.A(5R) mice (IAb, IEb/k) gave only IEb/k-restricted T cell clones even though IAb-restricted responses could be induced in C57BL/6 mice (IAb). These results indicated that IAk was preferred over IEk and IEb/k was preferred over IAb for presentation of ABA-Tyr. A comparison between IAk and IEb/k made by immunizing [B10.BR x B10.A(5R)]F1 mice (IAk, IEk, IAb, IEb/k), showed that IEb/k was favored over IAk. No IAb- or IEk-restricted response was seen. Further attempts were made to compare Ia preference for ABA-Tyr presentation by competitive inhibition assays. It could be shown that the presence of IEb/k molecules on an accessory cell interfered with the ability of IAb molecules on the same cell to present ABA-Tyr to an IAb-restricted T cell clone by direct competition. Such a competition was not observed between IAk and IEk. Finally, it could be shown that addition of ABA-Tyr inhibited the presentation of moth cytochrome-c peptide (81-103) by IEb/k but did not influence its presentation by IEk. From these functional studies we suggest that the binding affinity of ABA-Tyr with the Ia molecules will fall in the order: IEb/k greater than IAk greater than IAb greater than IEk.
Baskar
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Department of Pathology, Tufts University School of Medicine, Boston, MA 02111.
Leskowitz
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D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology*; D001391:Azo Compounds / Q000276:immunology*; D001667:Binding, Competitive; D002999:Clone Cells; D006241:Haptens; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D066298:In Vitro Techniques; D051379:Mice; D008815:Mice, Inbred Strains; D013601:T-Lymphocytes / Q000276:immunology*; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000276:immunology; D010132:p-Azobenzenearsonate / Q000031:analogs & derivatives / Q000276:immunology*
D001391:Azo Compounds; D006241:Haptens; D000949:Histocompatibility Antigens Class II; C024138:I-E-antigen; C000229:tyrosine-4-azobenzenearsonate; D014443:Tyrosine; D010132:p-Azobenzenearsonate