Further structural studies on the F9 (T/t) antigen(s)

The subunits of F9 (a product of a T/t allele) and H‐2 antigens were studied with regard to molecular weight and antigenicity. ³H‐labeled H‐2 and Relabeled F9 were reduced, mixed and electrophoresed on 4 different concentrations of acrylamide in order to detect differences between their carbohydrate moieties as well as their polypeptide chains. The major subunit (mol. wt. 44 000) of the 2 antigens co‐electrophoresed at each gel concentration. Rabbit sera raised against rat β₂ ‐microglobulin (β₂M), spleen cells and teratoma cells were used to immunoprecipitate molecules from lysates of radiolabeled splenocytes and teratocarcinoma cells. The anti‐spleen and anti‐β₂ M sera failed to deplete lysates of F9 antigen which could be subsequently bound by specific syngeneic antiserum. In contrast, rabbit anti‐F9 depleted > 80 % of F9 molecules from the lysate. The rabbit anti‐spleen and anti‐β₂M sera depleted H‐2 from spleen cell lysates but the anti‐F9 did not. These results suggest that neither the large nor the small subunits of H‐2 and F9 are immunologically cross‐reactive using rabbit sera.