Different populations of rheumatoid adherent cells mediate activation versus suppression of t lymphocyte proliferation

Adherent cells from synovial tissue of rheumatoid arthritis patients were fractionated on Percoll density gradients and analyzed to determine phenotypes, effects on allogeneic T lymphocyte proliferation, and production of prostaglandin E2 (PGE2). Cells expressing HLA-DR predominated in all fractions, and esterase-positive cells were enriched in light fractions. Heavy cells were potent stimulators in the mixed lymphocyte reaction and produced little PGE2, whereas light cells suppressed the mixed lymphocyte reaction and produced a large quantity of PGE2. These results suggest that macrophage-like synovial cells that suppress T helper lymphocyte activity are generated secondary to synovial lymphocyte activation in rheumatoid arthritis.