In particular, M1 polarized macrophages are the first line of defense against intracellular pathogens through mechanisms of endocytosis, production of reactive oxygen species (ROS), increase of antigen-presenting ability, and also by the induction of a Th1 switch on CD4 T cells, which in turn potentiate the response against infections (Atri et al., 2018). Here, CD4 is linked to infection.