Inhibitory effects of interferon-gamma on the T suppressor cell circuit in contact sensitivity.

The effects of a partially purified, splenocyte-derived murine interferon (MuIFN-gamma N) and a recombinant IFN-gamma (MuIFN-gamma R) on the T suppressor pathway and on the T effector cells of delayed type hypersensitivity were investigated in a 2,4-dinitrofluorobenzene contact sensitivity model. Various T cell subpopulations, suppressor T cells of afferent and efferent types, and an auxiliary T suppressor cells as well as a T effector cell of delayed type hypersensitivity were induced and the functions assessed in transfer experiments. Confirming the results of earlier experiments obtained with IFN-alpha, beta, the MuIFN-gamma N preparation and the rec. MuIFN-gamma R: enhanced the decreased response in animals sensitized with an antigen overload to an optimal response; inhibited the afferent-acting T suppressor cell in vivo and in vitro; inhibited the Ts-eff response; blocked the auxiliary T suppressor cell response after intravenous injection to recipients of Ts-eff cells on day 0 and 1; and did not suppress the activity of the T effector cell of delayed type hypersensitivity in vivo and in vitro (the MuIFN-gamma R was not tested). We conclude that IFN-gamma preferentially inhibited the T suppressor cell circuit of contact allergy. These results are similar to our observations on the inhibitory effects of a pure interferon-alpha, beta on the regulatory T suppressor cell circuit in contact allergy. Selective suppression of different T subpopulations by IFN-gamma may be an important regulatory mechanism in delayed type hypersensitivity.