Interleukin I primarily acts on-

1. IL-1: It is a protein produced mainly by activated macrophages and monocytes. Its production is stimulated by antigens, toxins, and inflammatory processes but inhibited by cyclosporine and coicosteroids. 2. Functions: 1. IL-1 produced by APCs stimulates TH cells activation and proliferation (M/C function): - Induces IL-2 receptor expression on TH cells - Induces |MHC-II expression on APCs 2. B-cell: Promotes B-cell development and maturation. 3. Liver: Induces synthesis of acute phase reactant proteins. 4. Hypothalamus: induction of fever. 5. Macrophage and neutrophil activation: | expression of ICAM