Abstract
Macrophage migration inhibitory factor (MIF) exerts a plethora of biological functions. Pro-inflammatory functions can clearly be attributed to the highly purified recombinant MIF protein. Therefore, MIF endangers the infected organism by acting synergistically with microbial substances, thereby enhancing the inflammatory reaction and causing exaggerated inflammation that can lead to tissue damage and shock. However, experimental evidence is provided to suggest that MIF might be able to partially reconstitute the defective immune defense in post-septic patients. As an immune-compromised organism, e.g. after sepsis, is protected from hyper-inflammatory shock, MIF can safely be applied without increasing the risk of shock. Thus, MIF does not act like a conventional cytokine but, rather, indirectly modulates and supports the immune response.