IL‐2 is also a representative multifunctional cytokine mainly secreted by CD4+ T cells in the Th1‐type immunity, which can activate T cells and promote cytokine production, activate macrophages, enhance the killing activity of NK cells, and promote the production of immunoglobulins by B cells, playing an essential role in the body's anti‐TB immunity. This evidence concerns the gene CD4 and tuberculosis.