Increased expression of extracellular matrix metalloproteinase inducer in rheumatoid synovium. 
To investigate the expression of extracellular matrix metalloproteinase inducer (EMMPRIN) in the synovial membrane of patients with rheumatoid arthritis (RA) and osteoarthritis (OA).  Mouse monoclonal antibody against human EMMPRIN was applied according to an avidin-biotin-peroxidase complex method to reveal EMMPRIN expression.  Western blotting and reverse transcriptase-polymerase chain reaction (RT-PCR) were performed to check for the presence of EMMPRIN protein and messenger RNA (mRNA).  EMMPRIN immunoreactivity was more intense in RA than in OA synovial membrane (P < 0.01).  EMMPRIN staining was more widespread in RA than in OA, especially in association with macrophage infiltrates.  RT-PCR of synovial membrane samples disclosed the presence of EMMPRIN mRNA.  Nucleotide sequencing of the PCR amplification products confirmed the identity of the amplified bands.  Immunoblot analysis revealed 55-kd glycosylated EMMPRIN bands, which were particularly prominent in RA samples.  The expression of EMMPRIN is upregulated in the rheumatoid synovial membrane.  EMMPRIN can induce local production of at least MMPs 1, 2, and 3, and can thereby play a role in joint destruction in RA.