Epitopes associated with the MHC restriction site of T cells. I. Selective expression of Iat epitopes on H-2-restricted helper T cells.
We previously established monoclonal antibodies (mAb) that are putatively directed to the I region of H-2k but are reactive only with T cells. Because of their specificity to the unique epitopes different from class II antigens, they are designated as anti-Iat reagents. The present study demonstrated that these anti-Iat inhibit the H-2k-restricted helper T (Th) cell function by acting on the very H-2 restriction site of both H-2k and H-2kxb F1 T cells. This was determined by both the cytotoxic treatment and blocking of antigen-primed Th cells. In the F1 Th population, only those restricted to H-2k were eliminated, leaving the H-2b-restricted Th cells uninhibited. The inhibition of the response was not due to the induction of suppressor T cells, but to the elimination of the function of radioresistant Lyt-1+,2- Th cells. Iatk epitopes were also found on an H-2k-restricted but not on H-2b-restricted Th cell clone established from the same H-2kxb F1 animal. None of the anti-Iatk were reactive with class II antigens on B cells. These results indicate that Iat epitopes are not directly encoded by the I region genes, but are associated with the H-2 restriction site of T cells, which see the self class II polymorphism. Thus, Iat epitopes are expressed clonally in high frequency on H-2k-restricted Th cells of F1, being excluded from the H-2b-restricted Th population. The relationship between Iat and T cell receptor molecules is unknown.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000939:Epitopes; D006183:H-2 Antigens / Q000276:immunology*; D006239:Haplotypes; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D008211:Lymphocyte Cooperation; D008285:Major Histocompatibility Complex; D051379:Mice; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000939:Epitopes; D006183:H-2 Antigens; D000949:Histocompatibility Antigens Class II