MIA (melanoma inhibitory activity): a potential serum marker for rheumatoid arthritis

Objective. MIA (melanoma inhibitory activity) is correlated with metastasis in patients with malignant melanoma. As MIA is not only produced by melano ma cells, but also by differentiated chondrocytes, we examined whether seru m levels of MIA are correlated with inflammation and/or joint destruction i n rheumatic diseases. Methods. MIA serum concentrations of patients with different rheumatic dise ases were examined and compared with healthy individuals and malignant mela noma patients. In addition, MIA concentrations were correlated to inflammat ory parameters and joint destruction. Results. Increased MIA serum concentrations were found only in patients wit h rheumatic diseases associated with joint destruction, such as rheumatoid arthritis (RA), osteoarthritis, HLA B27-associated oligoarthritis, and psor iatic arthritis. Of these rheumatic diseases, a significant increase in MIA serum concentrations was seen only in patients with RA, associated with rh eumatoid factor (RF) positivity and joint destruction. Conclusions. In addition to RF, MIA might therefore be useful in the differ ential diagnosis of RA vs non-destructive rheumatic diseases, and the prese nce of elevated levels of MIA in serum very likely reflects joint destructi on in RA.