Abstract

Based on their cytokine profile, CD4 + T helper (Th) cells can be divided into several kinds. Th1 and Th2 cells are characterised by these polarised patterns of cytokine production, and they may be separated from one another functionally by producing lFN- and IL-4, respectively. The kind of immune response that arises following antigen priming depends on these characteristics. They lack distinguishing surface indicators, and single-cell characterisation by cytokine immunoassay or mRNA analysis is constrained in both cases. We have investigated the formation of Thl and Th2 cells in response to antigen exposure and the patterns of cytokine generation in established T cell clones using immunofluorescent detection of intracellular IFN-/and IL-4. By 4 hours, almost all cells had IFN- production that could be detected, and the majority of cells continued to produce IFN- for >24 hours.At 4 hours, Th2 cell IL-4 output peaked before falling down quickly. Fewer cells generated IFN-% in Th0 cells that contained both cytokines; this phenomenon did not emerge until the production of IL-4 decreased. Clone cocultivation failed to reveal any such cross-regulation. Th2 cells were produced after antigen-stimulated transgenic T cells expressed an ovalbumin-specific T cell receptor, most likely as a result of natural IL-4 synthesis. Thl cells appeared when IL-12 and/or anti-IL-4 were added, although some Th0 cells appeared when IL-12 was administered alone.