<prompt> Classical pathway macrophage activating moleculeIFN gammaIL 4IL 13ILI  <response>: Answer- A. IFN gammaThere are two major pathways of macrophage activation:Classical macrophage activation- induced by microbial products, which engage toll like receptors other sensors, by T cell derived signals, impoantly the cytokine IFN-yAlternative macrophage activation - induced by cytokines III ILl3 produced by T lymphocytes other cells. Their main function is tissue repair secrete growth factors which cause angiogenesis, activate fibroblasts stimulate collagen synthesis. 