Isolation of an antigen-specific T suppressor factor that suppresses the in vivo response of DBA/2 mice to ferredoxin.

A T cell hybridoma (Fd11) has been produced from B10.D2 mice that secretes a putative antigen-specific T suppressor factor (TsF). The TsF is isolable from culture supernatants of Fd11 by affinity purification over columns containing either a monoclonal antibody (B16G) shown previously to be capable of binding murine TsF or ferredoxin (Fd), the nominal antigen to which the Fd11 TsF binds. Specificity of the Fd11 TsF for Fd was established by comparing it to another TsF isolated by us (A10 TsF) in a sandwich ELISA, and by demonstrating the specific reactivity to Fd of the hybridoma in calcium flux studies. The Fd11 affinity-purified TsF was shown to contain two major unique components with m.w. in the region of 80,000 and 35,000 when run on reducing polyacrylamide gels in the presence of sodium dodecyl sulphate. Specific immunosuppressive properties of Fd11 were demonstrated when Fd11 TsF (10 micrograms) was injected i.v. into Fd-primed syngeneic mice at the time of antigen boost. Fd11 TsF specifically and significantly diminished the secondary antibody response to Fd in DBA/2 mice.