Serologic, biologic, and western blot analysis of a T suppressor factor with specificity for the hapten 4-hydroxy-3-nitrophenyl acetyl derived from serum-free medium.

A T cell hybridoma producing a T suppressor factor (TsF) with specificity for the hapten nitrophenyl was converted to long term growth in serum-free medium and its product tested by serology, bioactivity, and Western blot analysis. Results indicated that Ag-specific suppressive activity was present in serum-free medium and this TsF could exhibit the characteristics ascribed to it by various groups: it could bind nominal Ag with specificity, it was bound by anti-TsF mAb, and it could mediate Ag-specific suppression both in vivo and in vitro. Western blot and SDS-PAGE analysis of this purified TsF revealed a 43-kDa single chain protein.