Altered interleukin‐2 secretion in patients with primary fibromyalgia syndrome

Interleukin‐2 (IL‐2) production was studied in T lymphocytes and isolated CD4+ T lymphocytes from 12 patients with primary fibromyalgia syndrome and 10 healthy volunteers. The dose and time kinetics of IL‐2 production by concanavalin A‐stimulated T cells and CD4+ T cells of fibromyalgia patients differed from findings in controls by 1) a need for a higher concentration of mitogen in order to achieve optimal IL‐2 secretion, and 2) a delay in the peak time of optimal IL‐2 secretion. Unlike normal IL‐2 secretion, which was higher after removal of CD8+ T cells, the pattern and degree of IL‐2 secretion by cells from fibromyalgia patients were not changed following removal of CD8+ T cells. Addition of calcium ionophore in assays using suboptimal concanavalin A concentrations did not correct the reduction in IL‐2 secretion by fibromyalgia patient T cells, but addition of phorbol myristate acetate induced normal secretion of IL‐2. These findings suggest that there is a defect in the IL‐2 pathway, which is related to protein kinase C activation and does not involve impairment of Ca 2+ elevation, in patients with fibromyalgia.