Inhibition signals have veto power over activation signals. Inflammatory reaction in response to cytokine release by activated TH cells. Takes at least 24 hr and peaks at 48-72 hr after initial contact. TDTH cells secrete cytokines. Cytokines attract monocytes, which adhere to vascular endothelial cells and migrate to the affected regions.
Monocytes differentiate into macrophages.
Macrophages upregulate MHC-II and adhesion molecules. Macrophages exhibit phagocytosis and killing.