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 cel ls 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-gamma- a nd IL-4-producing cells in these two subpopulations using ELISPOT assays. W e found that the CD4(+)CD45RC(-)RT6(+) subset showed higher numbers of IL-4 -producing cells than the CD4(+)CD45RC(+)RT6(-) subset and, though less pro nounced, that the latter demonstrated higher numbers of IFN-gamma producers . Therefore, we conclude that our results provide evidence for the existenc e of phenotypically defined Th1 and Th2 cells in the rat. This is supported by the finding that the ratios of IFN-gamma/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/RT 6 ratio, whereas the reverse was true for strains susceptible to a Th2-medi ated autoimmune disease. (C) 2000 Academic Press.