[Induction of rheumatoid factor-like substance and synovial lining cell hyperplasia in rats immunized with heat-killed Escherichia coli 0:14].

Histological changes in the ankle joints and serum anti-IgG rheumatoid factor-like substance detected by enzyme-linked immunosorbent assay (ELISA) were investigated in Sprague Dawley (SD), Wistar, and Lewis rats immunized with heat-killed Escherichia coli 0:14. Synovial lining cell hyperplasia was observed in 23 of 46 joints and pannus formation in 7 of 46 joints in SD rats immunized for 29 weeks. RFLS levels were elevated from the 15th, 7th, and 5th week of immunization in rats receiving doses of 0.1, 1, and 10 mg of E. coli respectively, and remained elevated dose-dependently. RFLS levels in SD and Wistar rats were significantly higher (p less than 0.01) than in Lewis rats during the period from the 7th to the 13th week of immunization. These results imply that immunization of rats with E. coli induces arthritic changes in the ankle joints and produces RFLS in the serum in a dose-dependent and different manner in each rat strain.