Plaque-forming, antibody-dependent, cytotoxic cells with monocytic properties are present in rheumatoid synovial tissue.

Mononuclear cells eluted from synovial tissues from 16 patients with rheumatoid arthritis (RA) and 4 patients with juvenile rheumatoid arthritis (JRA) mediate cytotoxicity in vitro against a monolayer of sheep erythrocytes sensitized with IgG. Cell fractionation experiments suggested that most of the plaque-forming cells were non-lymphocytic and had adherence and phagocytic properties.