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 melanoma cells, but also by differentiated chondrocytes, we examined whether serum levels of MIA are correlated with inflammation and/or joint destruction in rheumatic diseases. METHODS MIA serum concentrations of patients with different rheumatic diseases were examined and compared with healthy individuals and malignant melanoma patients. In addition, MIA concentrations were correlated to inflammatory parameters and joint destruction. RESULTS Increased MIA serum concentrations were found only in patients with rheumatic diseases associated with joint destruction, such as rheumatoid arthritis (RA), osteoarthritis, HLA B27-associated oligoarthritis, and psoriatic arthritis. Of these rheumatic diseases, a significant increase in MIA serum concentrations was seen only in patients with RA, associated with rheumatoid factor (RF) positivity and joint destruction. CONCLUSIONS In addition to RF, MIA might therefore be useful in the differential diagnosis of RA vs non-destructive rheumatic diseases, and the presence of elevated levels of MIA in serum very likely reflects joint destruction in RA.