Gelatinase B in chronic synovitis: immunolocalization with a monoclonal antibody.

Gelatinase B is a matrix metalloproteinase (MMP-9) involved in the remodelling of extracellular matrices of connective tissues. With the use of specific monoclonal antibodies against human gelatinase B, the producer cell types were pinpointed in histopathological sections of a number of arthritic diseases. In cases of acute joint trauma, chondromatosis, villonodular synovitis and a cyst of a bursa, high numbers of strongly immunopositive neutrophils were observed in addition to weaker staining macrophages. Activated macrophages with giant cell morphology clearly stained with the gelatinase B-specific monoclonal antibody in the case of villonodular synovitis and in an epidermoid cyst. However, in the sections from patients with rheumatoid arthritis, no immunostaining was seen. In other cases of chronic synovitis, however, within the lymphocyte nodular aggregates a strong gelatinase B expression was observed in morphologically identified dendritic cells. In conclusion, gelatinase B production in joint disease seems to be predominantly by neutrophils and cell types of the macrophage/antigen-presenting cell lineage.