Reconstitution of an inactive antigen-specific T cell suppressor factor by incubation of the factor with prostaglandins.

Experiments were performed to test the hypothesis that prostaglandins are crucial to the ability of an antigen-specific T cell suppressor factor to deliver a suppressive signal. In the system employed, T suppressor cells release an antigen-specific factor (TsF) that suppresses the ability of effector cells to transfer contact sensitivity (CS) skin swelling responsiveness to adoptive recipients. Culture of TsF-producing cells in the presence of indomethacin caused production of an inactive TsF that could be reconstituted by incubation of this inactive factor with low concentrations of certain prostaglandins such as PGE2 or PGE1. Subsequently, nearly all the prostaglandins were removed by dialysis, and the reconstituted TsF then acted as an antigen-specific suppressor of CS effector cells. Neither the inactive factor nor prostaglandins were suppressive alone. Furthermore, the prostaglandins are crucial to the constitution of TNBSA-F, the non-antigen-binding subunit of the TsF that probably delivers the ultimate suppressive signal. These results provide a new type of antigen-specific role for prostaglandins in immunoregulation and indicate that simple, local, hormonal molecules in physiologic concentrations can have a crucial and long-lasting role in constituting the suppressive activity of antigen-specific regulatory macromolecules released by suppressor T cells.