Serologic and Biochemical Studies of the Ia System of the Mouse H-2 Gene Complex. Further Evidence for an I-C Subregion

Abstract

Three antisera were made against B10.A(5R) tissues to show the presence of an I-C^d subregion in that strain: 1) B10 anti-B10.A(5R) [anti-D^d, I-C^d]; 2) (B10 × C3H.OL) F₁ anti-B10.A(5R) [anti-D^d]; 3) (B10 × HTI)F₁ anti-B10.A(5R) [anti-I-C^d]. Serologic analyses of the antisera clearly showed the presence of an I^d segment in B10.A(5R) and provided further evidence for the existence of a new I-C subregion. These anti-I-C^d sera define the Ia.7 specificity and analyses of several recombinants map Ia.7 within the I-C subregion. Ia.7 is present in I-C^k, I-C^d and I^p strains. Biochemical analyses showed that the Ia.7 molecule has a molecular weight of 31,000 and is distinct from the 46,000 m.w. H-2K or D molecules. The possible roles of the I-C region in immune response, mixed lymphocyte reaction, and graft-vs-host reaction are discussed.