The cytokine profile within the rheumatoid nodule (i.e., presence of IFNgamma but not IL-2, and prominent expression of IL-1beta and TNFalpha together with IL-12, IL-18, IL-15, and IL-10) is similar to the profile of cytokines in the synovial lesion of rheumatoid arthritis, which is generally accepted as being attributable to a Th1-mediated inflammatory mechanism.
Cytokine content (tumor necrosis factor alpha [TNFalpha], interleukin-1beta [IL-1beta], and IL-1 receptor antagonist [IL-1Ra]), at the messenger RNA (mRNA) and protein levels, and cell adhesion molecule expression were studied in 16 rheumatoid nodules and 6 synovial membranes.