Rheumatoid Arthritis Research Today is a free monthly online journal that collates and summarizes the latest research about Rheumatoid Arthritis, including details on treatment, symptoms, causes, medication.

Effectiveness of anti-folate receptor beta antibody conjugated with truncated Pseudomonas exotoxin in the targeting of rheumatoid arthritis synovial macrophages.

Nagayoshi R, Nagai T, Matsushita K, Sato K, Sunahara N, Matsuda T, Nakamura T, Komiya S, Onda M, Matsuyama T

Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.

OBJECTIVE: To define the distribution of folate receptor beta (FRbeta)-expressing cells in various tissues, including rheumatoid arthritis (RA) synovial tissues, and to verify the effects of an immunotoxin composed of an anti-FRbeta monoclonal antibody (mAb) and truncated Pseudomonas exotoxin A (PEA) on apoptosis and tumor necrosis factor alpha (TNFalpha) production by adherent synovial mononuclear cells from RA patients. METHODS: Anti-FRbeta mAb were produced by immunizing mice with FRbeta-transfected murine pre-B cells. The distribution of the FRbeta antigen was examined by immunohistochemical analysis using anti-FRbeta mAb and macrophage-specific anti-CD163 mAb. Anti-FRbeta mAb was chemically crosslinked with truncated PEA. FRbeta-expressing macrophages were produced by the transfection of adenovirus vector containing the FRbeta gene. Apoptotic cells were detected by staining with propidium iodide. TNFalpha was measured by enzyme-linked immunosorbent assay. RESULTS: FRbeta-expressing cells were not present in peripheral blood leukocytes and their activated cells. In all of the tissues examined, most FRbeta-expressing cells were CD163+. The immunotoxin significantly induced the apoptosis of FRbeta-transfected macrophages and adherent RA synovial mononuclear cells and inhibited TNFalpha production by adherent RA synovial mononuclear cells. CONCLUSION: We demonstrated the limited distribution of FRbeta-expressing cells in various tissues. The immunotoxin targeting FRbeta-expressing cells will provide a therapeutic tool for rheumatoid synovitis.

Published 12 September 2005 in Arthritis Rheum, 52(9): 2666-75.
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