Single Expression of CD45RC and RT6 in Correlation with T-Helper 1 and T-Helper 2 Cytokine Patterns in the Rat

Previous studies involving the function and development of peripheral T cells have proposed that, in the rat, CD4+CD45RC+RT6− and CD4+CD45RC−RT6+ T-cell subsets may represent Th1 and Th2 cells, respectively. Here we tested this hypothesis directly by analyzing frequencies of IFN-γ- and IL-4-producing cells in these two subpopulations using ELISPOT assays. We found that the CD4+CD45RC−RT6+ subset showed higher numbers of IL-4-producing cells than the CD4+CD45RC+RT6− subset and, though less pronounced, that the latter demonstrated higher numbers of IFN-γ producers. Therefore, we conclude that our results provide evidence for the existence of phenotypically defined Th1 and Th2 cells in the rat. This is supported by the finding that the ratios of IFN-γ/IL-4 and CD45RC/RT6 correlated positively among various rat strains. Finally, rat strains susceptible to induction of a Th1-mediated autoimmune disease showed the highest CD45RC/RT6 ratio, whereas the reverse was true for strains susceptible to a Th2-mediated autoimmune disease.