HIGH-CONCENTRATIONS OF THE MACROPHAGE-MIGRATION INHIBITORY FACTOR IN HUMAN SEMINAL PLASMA AND PROSTATIC TISSUES

During purification procedures to isolate kallikrein hK2 from human se minal plasma, kallikrein hK2 was found to be associated with another p rotein after several chromatographic steps. This study was conducted t o identify the hK2 companion protein and characterize its properties a nd distribution. The protein was identified as macrophage migration in hibitory factor (MIF) by its NH2-terminal amino acid sequence. It had an enzymatic activity identical to that of recombinant MIF. Its concen tration varied between 1 and 10 mu g/mL in various seminal plasma. By immunohistochemical analysis, MIF was found to be localized mainly in the epithelial cells of normal and cancerous prostates. Since MIF is a well-known proinflammatory mediator, these results suggest that it ma y have important functions in both human reproduction and prostatic ph ysiology.