FREQUENCIES OF T-CELLS SECRETING IL-2 AND OR IL-4 AMONG UNPRIMED CD4+ POPULATIONS - EVIDENCE THAT CLONES SECRETING IL-2 AND IL-4 GIVE RISE TO CLONES WHICH SECRETE ONLY IL-4

We have utilized a limiting dilution assay, involving a minimum of in vitro culture, to determine the frequencies of CD4+T cells which have the capacity to secrete IL-2 (Th1), IL-4 (Th2) or IL-2 and IL-4 (Th0). CD4+ lymph node cells obtained from unimmunized mice were found to contain 40% Thl, 34% Th2, and 26% Th0 cells. The fact that Th0 cells could be identified in cell populations obtained from unimmunized mice suggested a possible role for Th0 in the differentation pathways of Th1 and Th2. Antigen-specific Th0 clones were thus established and observed to convert to a Th2 phenotype after prolonged culture. The relevance of these findings is discussed in the context of current models of CD4+ T cell subsets. © 1990.