Studies of histamine in the rheumatoid joint.

Fragments of synovial membranes from three patients with rheumatoid arthritis were incubated in Dulbecco's modified Eagle's medium (DMEM). Histamine was released into the medium at rates up to 649.3 ng/g synovium/day. To investigate whether histamine in synovial fluid may have more than a vasoactive role, cells cultured from human trabecular bone adjacent to a rheumatoid joint and human adherent rheumatoid synovial cells were incubated with different concentrations of histamine for 5 min. Histamine increased the intracellular content of cyclic AMP up to three fold in a dose-related manner but had no effect on synovial cells. This offers preliminary evidence that cells grown from human trabecular bone have histamine receptors.