Interleukin-1 expression by neutrophils in rheumatoid arthritis.

OBJECTIVE To determine if neutrophils from blood and synovial fluid of patients with rheumatoid arthritis and other joint arthropathies express interleukin-1 beta mRNA. METHODS RNA was isolated from neutrophils from patient and control blood, and synovial fluid of patients, probed in northern blots, and quantified by densitometry. It was also isolated and analysed from control blood neutrophils after incubation in vitro with granulocyte macrophage colony stimulating factor (GM-CSF). RESULTS Neutrophils from the synovial fluid of patients with rheumatoid arthritis contained low levels of mRNA for interleukin-1 beta--between 0.1 and 2% of those observed during stimulation of control neutrophils with GM-CSF for one hour. Higher levels (4-40% of the maximal GM-CSF values) were observed in blood neutrophils from patients with rheumatoid arthritis. CONCLUSIONS Neutrophils contribute to the cytokine network in rheumatoid arthritis. In some circumstances, activation of transcription may occur within the circulation of these patients.