MIF is a proinflammatory cytokine involved in many inflammatory reactions and disorders. MIF (macrophage migration inhibitory factor) was one of the first cytokines to be discovered and was initially described as a T cell-derived factor that inhibits the random migration of macrophages (Weiser 1989). Recently, MIF was rediscovered as a pituitary hormone that act as the counterregulatory hormone for glucocorticoid action within the immune system (Bernhagen 1993, Mitchell 1995). MIF was released from macrophages and T cells in response to physiological concentrations of glucocorticoids. The secreted MIF counter-regulates the immunosuppressive effects of steroids on immune cell activation and cytokine production (Bucala 1998). MIF plays a critical role in the host control of inflammation and immunity. MIF is involved in both autoimmune disorders and tumorigenesis.

Secreted. Cytoplasm. Note: Does not have a cleavable signal sequence and is secreted via a specialized, non-classical pathway. Secreted by macrophages upon stimulation by bacterial lipopolysaccharide (LPS), or by M.tuberculosis antigens.