The Non-Specific Immune Effect of BCG on Instinct Immune Cells

Inate immune cells are things like macrophages, natural killer cells. They're the first line defense against an infection that gets into the lung or the bloodstream. Some exposures and BCG is one of them will modify those innate immune cells epigenetically. So they alter some of the things that bind to DNA so that they are more responsive when they encounter a pathogen.