The relative proportions of secreted interleukin-2 and interleukin-10 determine the magnitude of rheumatoid arthritis T-cell proliferation to the recall antigen tuberculin purified protein derivative

Objective. To investigate the mechanisms of the deficient proliferative responses by rheumatoid arthritis (RA) peripheral blood T cells to the recall antigen tuberculin purified protein derivative (PPD). Methods. The concomitant production of interleukin (IL)-2, IL-10 and lymphocyte proliferation were studied by enzyme-linked immunosorbent assay and [H-3]thymidine uptake, respectively, in 12 normal controls and eight RA patients. Results. An inverse correlation was found between IL-10 production and proliferation to PPD. The proliferative response was shown to be critically affected by the IL-2:IL-10 ratio so that absolute levels of secreted IL-2 or IL-10 correlated non-significantly with lymphocyte proliferation. Conclusion. The deficient T-cell proliferation in RA peripheral blood mononuclear cells is related to the relative proportions of IL-2:IL-10 rather than the absolute amounts secreted.