Fibromyalgia (FM) is a clinical entity of unknown etiology frequently diagnosed in rheumatology. The potential involvement of the immune system in its pathogenesis has been suggested. Studies of abnormal T cell subpopulations often have been inconclusive. We attempted to clear this point by comparing lymphocyte subpopulations, including some of the newer activation markers, in patients with FM and healthy controls.
Sixty-five patients with FM and 56 healthy controls were studied. Flow cytometry was used as a quantification technique to measure lymphocyte subpopulations, CD3 (T cells), CD19 (B cells), CD16 (natural killer cells), CD4 (T helper/inducer cells), CD8 (T cytotoxic/suppressor cell), CD25 (interleukin 2 receptor), CD69 (activation inducer molecule marker), CD71 (transferrin receptor) and CD54 (ICAM-1); CD4/CD8 ratios were also estimated.
The number of T cells expressing activation markers CD69 and CD25 was decreased in patients with FM; the other subpopulations were similar in patients and controls.
Our results suggest a defect in T cell activation in patients with FM.