MIF also known as MMIF is a lymphokine involved in cell-mediated immunity, immunoregulation, and inflammation. MIF plays a crucial role in modulating macrophage and T cell functions, making MIF an essential regulator of host immune response to infection. MIF is primarily produced by the pituitary gland and is expressed in various cell types, including monocytes, macrophages, and differentiating immunological cells in the eye lens and brain, as well as fibroblasts. MIF is found at sites of inflammation, indicating MIF′s significant role in regulating macrophage activity during host defense. Elevated levels of MIF have been associated with severe sepsis and septic shock, where MIF enhances the production of other inflammatory cytokines such as tumor necrosis factor α, interleukin-1, and interferon-γ, thereby promoting a systemic inflammatory response.