Sex differences in in vitro pro-inflammatory cytokine production from peripheral blood of multiple sclerosis patients

We compared the patterns of the pro-inflammatory cytokines, interferon-γ (IFN-γ), interleukin-2 (IL-2) and tumor necrosis factor-α (TNF-α), and the anti-inflammatory cytokines, interleukin-10 (IL-10) and tumor growth factor-β (TGF-β) from peripheral blood of male and female patients with relapsing-remitting (RR) and secondary progressive (SP) forms of multiple sclerosis (MS). The relationships between pro-inflammatory cytokines and disability (expanded disability status scale, EDSS) were also examined. Peripheral blood anti-coagulated with heparin was obtained from 47 MS patients (30 women and 17 men) and activated with phorbol-12-myristate 13 acetate (PMA) and ionomycin in the presence of brefeldin A and stained for flow cytometry with fluorescently labeled antibodies against intracellular IFN-γ, TNF-α, IL-2, IL-4 and IL-10. The T cells were delineated with peridinin chlorophyll protein (Per-CP) labeled anti-CD3 antibody. The stained samples were analyzed on a flow cytometer to assess the intracellular pro-inflammatory cytokine patterns. The levels of interleukin-10 (IL-10) and tumor growth factor-β (TGF-β) were measured in plasma using enzyme-linked immunoassay. The percentage of TNF-α-producing CD3 positive cells was significantly higher (P=0.045) in men (mean±S.D., 39±13%) than in women (mean±S.D., 29±13%) RR-MS patients. The percentage of CD3 positive cells producing IFN-γ was significantly correlated with EDSS in females but not in males (Spearman rank correlation r_S=0.49, P=0.018). The secretion of the pro-inflammatory cytokines, IFN-γ and TNF-α, is influenced by gender in MS patients and may contribute to the sexual dimorphism of MS.