Con A-Inducible Suppression of MLC: Evidence for Mediation by the TH2+ T Cell Subset in Man

Abstract

Human peripheral lymphoid cells pretreated with Concanavalin A for 48 hr can markedly suppress the proliferative response of untreated autologous lymphoid cells in MLC. Isolation studies with Sephadex G-200 anti-F(ab′)₂ affinity chromatography, nylon adherence, and E rosetting indicate that the Con A-induced suppressor cell is a T cell. Further fractionation into TH₂⁺ and TH₂^- cell subsets with an equine-anti TH₂ serum show that both subsets can be activated by Con A to an equivalent degree. After activation only the TH₂⁺ subset can suppress autologous responder cells in MLC. The TH₂^- subset, which comprises 80% of peripheral human T cells, although induced by Con A to proliferate, cannot itself suppress the MLC response. Nevertheless, the TH₂^- subset can be shown to modulate the generation of suppressor TH₂⁺ cells at 24 hr but not at 48 hr. These studies support the notion that the Con A-induced suppressor cell is confined to a distinct T cell subset in man and that T-T interactions are important in the overall expression of the immune response.