To investigate whether human T cells produce GM-CSF during infection, peripheral blood mononuclear cells (PBMC) from active TB patients (TB) or healthy controls (HC) were stimulated or not with M. tuberculosis lysate, and the production levels of GM-CSF and IFN-γ by CD4+ T cells and CD4− T cells were determined by flow cytometry (see Fig. S1 in the supplemental material for the gating strategy). The gene discussed is CD4; the disease is tuberculosis.