Reactions and crossreactions of a rabbit anti-H2 antigen serum.

A rabbit antiserum raised against highly purified, papain-solubilized H-2d antigens contained two sets of non-crossreacting antibodies directed against each one of the two H-2 antigen subunits. The antiserum recognized only 12,000 and 47,000 dalton polypeptide chains when splenocyte membrane glycoproteins were analysed. Among the molecules precipitated with the rabbit antiserum all H-2K and D antigens were present. In addition to regular H-2K and D antigens minor amounts of material with the typical H-2 antigen subnit structure, but lacking alloantigenic determinants, were precipitated by the antiserum. These 'non-H-2 antigens' were produced in relatively greater amounts by T-cells than by B-cells. Both sets of antibodies in the rabbit antiserum reacted with the TL antigens demonstrating that there is an immunological crossreactivity between the classical alloantigenic H-2 antigen chain and the alloantigenic TL antigen chain. The F9 cell line, believed to represent cells at the morula stage, display H-2 antigen-like structures as revealed by the rabbit antiserum.