Soluble factors in tolerance and contact sensitivity to 2,4‐dinitrofluorobenzene in miceIV. Characterization of migration inhibition factor‐producing lymphocytes and genetic requirements for activation

The production of migration inhibition factor (MIF) in vitro by lymph node cells from mice with contact sensitivity to 2,4‐dinitrofluorobenzene (DNFB) was investigated. MIF activity of cell‐free culture supernatants was measured using a micro, indirect “hanging‐drop” assay system. We found that DNFB‐sensitized lymph node cells are stimulated to produce MIF by co‐culture with DNP‐labeled spleen cells or splenic adherent cells. The stimulation was quantitatively antigen‐specific, as co‐culture with TNP‐spleen cells or TNP‐splenic adherent cells induced only low levels of MIF activity. Pretreating the immune lymph node cells with different antisera plus complement, before addition of DNP‐spleen cells, showed that MIF production is dependent on Ia− T cells. Additional experiments showed that in order for the T cells to be stimulated, homology at the I‐A subregion of the major histocompatibility complex between the T cells and DNP‐spleen cells is required. Collectively, these results correlate with our previous finding that transfer of contact sensitivity is mediated by Ia− T cells and indicate that both tests, i.e., transfer in vivo and MIF production in vitro, are measuring effector functions of the same T cell subset.