CD8A and infection: This alternative way of CD8 T cell activation has great immunopathogenetic importance since pathogen antigens contained in the phagosome do not penetrate the cytoplasm and cannot be processed in the classical way with further presentation in complex with MHC I. It has been shown that macrophages immediately after infection with M. tuberculosis, lose the ability to present mycobacterial antigens and activate CD8 T cells [173].