PRF1 and infection: Most of the effects on Mtb-infected cells are based on IFN-γ released by those lymphocytes that mediate Mφ activation, leading to a more microbicidal state [35] The cytotoxic effector cells that result from this cytokine-activated infection environment will contribute to the control of the infection via the release of granzyme–perforin-mediated macrophage apoptosis.