How is delayed type HS?

Activation of macrophages increases their production of toxic oxygen radicals, nitric oxide, and hydrolytic lysosomal enzymes enabling the killing of microbes within their phagolysosomes/ tissue damage. transform into multinucleated giant cells, whereas activated CD8+T cells destroy target cells on contact causing tissue injury, typically called delayed-type HS Activated macrophages secrete proinflammatory cytokines such as TNF-α, IL-1, and IL-6 ===> Leaky endothelial barriers => more immune cells => edema, redness and fever These cells release mediators (chemokines and cytokines) that activate local endothelial cells, recruiting an inflammatory cell infiltrate Each of these phases takes several hours and so the fully developed response appears only 24–48 hours after challenge