The isolation of an antigen binding factor from cultured murine T-lymphocytes

BALB/c mice were immunized with the random sequence polypeptide [Glu60 Ala40] (GA). 125I-lymphocyte suspensions were prepared from lymph nodes, radiolabelled with 125I and cultured for 18 hours. Supernatant fluids were collected and passed over an immunoabsorbant composed of [D-Glu60 D-Ala40] (D-GA) bound to Sepharose. The non-adherent fraction was then applied to GA Sepharose and the adherent material eluted with 2 M NaSCN. The eluate was relabelled with 125I, reabsorbed to GA Sepharose and eluted. This fraction bound well to GA-Sepharose (50-80%) but not to the enantiomorphic D-GA Sepharose (5-10%). This material did not react with goat antisera directed against murine IgG, IgM or IgA. It was capable of binding to rabbit antiidiotypic sera raised against BALB/c anti-GA, but not to those antibodies raised against BALB/c anti-GAT. It also showed some reaction with rabbit antiserum to a rat T cell factor (TCF). Polyacrylamide gel electrophoresis revealed a major component with an approximate molecular weight of 63,000 which was not affected by reduction and alkylation.