Interleukin-10 Production by Th1 Cells Requires Interleukin-12-Induced STAT4 Transcription Factor and ERK MAP Kinase Activation by High Antigen Dose Abstract Summary CD4+ T cells producing interleukin-10 (IL-10) and interferon-γ (IFN-γ) are reported in chronic infections. However, the signals that direct the development of IL-10-producing T helper 1 (Th1) cells are undefined. We showed that development of IL-10-producing T