Regulation of in Vitro Release of TH2 Type Cytokines (IL-4, IL-6) in the T Cell Response to the Trinitrophenyl (TNP) Hapten

We have investigated in vitro the ability of T cells from mice primed for contact hypersensitivity to release cytokines of the TH2 subtype, in particular IL-4 and IL-6. We demonstrate that both these cytokines are indeed produced by T cells from the lymph node and spleen of mice immunized by topical application of picryl chloride and restimulated in vitro by TNP-coupled spleen cells. However, the release of IL-4 is limited by the activity of IFN-γ, a TH1 cytokine which we have previously shown is also produced after contact sensitization. Finally, induction of tolerance to TNP, by intravenous administration of antigen, or transfer of cells from tolerant mice into naive donors prior to sensitization (which suppresses the contact sensitivity reaction in the recipients) leads to a fall in IL-4 production. Thus neither tolerance nor suppression in this system is mediated by the antagonistic activities of TH1 and TH2-type T cells. In contrast, IL-6 production is upregulated during both suppression and tolerance, suggesting that this cytokine may play a part in the negative regulation of contact sensitivity.