CD4 and infection: In vitro studies have shown that Th1 cells could be the source of this IL-10 in the control of infections with intracellular pathogens and these cells maintain their IFN-γ-producing function intact, and consequently activate macrophages or IL-10-producing Treg cells (CD4+CD25+) both in infection with L. major or with M. tuberculosis[23], [52], [53].