Stimulation by interleukin-7 of mononuclear cells in peripheral blood, synovial fluid and synovial tissue from patients with rheumatoid arthritis.

To determine how interleukin-7 (IL-7) affects the proliferation of T cells in patients with rheumatoid arthritis (RA), we evaluated the response of mononuclear cells (MNC) obtained from their peripheral blood (PB), synovial fluid (SF) and synovial tissue (ST) to stimulation by recombinant IL-7 and interleukin-2 (IL-2). Each cytokine was administered alone or combined with phytohemagglutinin (PHA). Cellular DNA synthesis was assayed by the [3H]-thymidine incorporation method. The stimulatory effect of 500 u/ml IL-7 on PBMNC obtained from 19 patients with RA was significantly lower than on PBMNC from 19 healthy controls. However, the same degree of stimulatory activity of 500 u/ml IL-2 was observed on the PBMNC from both RA patients and control subjects. The response of PBMNC to a suboptimal dose of PHA (0.2 micrograms/ml) was enhanced by adding either IL-7 or IL-2 (100 or 500 u/ml) to the cultures. The enhanced synthesis of DNA by both RA and control PBMNC on exposure to IL-7 following stimulation by a suboptimal dose of PHA was higher than that of IL-2. The effect of IL-7 on RA PBMNC was significantly greater than that of IL-2 at the concentration of 100 u/ml on PBMNC from the same RA patients. The stimulatory activity of IL-2 at the concentrations of 100 and 500 u/ml on SF MNC and ST MNC exceeded that of IL-7. In particular, an IL-2 dose of 500 u/ml had a marked effect on SF MNC. The PHA response of SF MNC was the lowest seen among the MNC from three different compartments.(ABSTRACT TRUNCATED AT 250 WORDS)