The in vivo response of TH1 and TH2 cells to challenge with specific antigen was examined with use of an adoptive transfer model. CD4+ T cells were isolated from DO 10 mice bearing an ovalbumin (OVA)-specific transgenic αβ-TCR. Following in vitro stimulation with OVA in the presence of IL4 or anti-IL4 plus EL-12 for polarization to the TH! or Tn2 phenotype, respectively, TH! or T}{2 cells were transferred to BALB/c recipients. The recipient mice were challenged with OVA in complete Freund's adjuvant and sequential samples obtained for analysis. Tissues were examined for in vivo cytokine production, surface marker phenotype, and anatomic localization of transgenic cells. In situ hybridization revealed that Tnl-cell recipients produced mostly IL2 and IFN-y, whereas TH2-celI recipients produced mostly IL4 and IL 10 The observed frequency of cytokine positive cells was surprisingly low. Significantly, the production of IFN-Y was associated with an increased production of ovalbumin-specific antibodies of the IgG2a isotype. Conversely, production of EL4 and DL10 were associated with an increased in the production of IgGl. The result suaeest that a verv small number of cvtokine producing cells can overtlv influence the phenotype of the immune response in vivo.
