Adherent synovial cells from both 13 patients without rheumatoid arthritis (RA) (gout, osteoarthritis and meniscal lesion) and 8 patients with RA consisted of dendritic cells, macrophage-like cells and fibroblast-like cells after cloning in a similar fashion as reported in our previous paper. All the adherent synovial cells from patients without RA did not release interleukin 1 (IL-1) beta and prostaglandin E2 (PGE2) spontaneously, while those cells released comparable amounts of IL-1 beta, but not PGE2 to RA cells after type II collagen stimulation. Only the synovial cells from RA, irrespective of morphology and cloning, released IL-1 beta and PGE2 without stimulation. Nonrheumatoid synovial cells may differ functionally from RA cells.