To evaluate whether the protective effect of estradiol on clinical signs of S. aureus-induced arthritis and bone loss could be mediated by modulation of the systemic cytokine responses, we analyzed the serum protein levels of the proinflammatory cytokines TNF-α, IL-6, IFN-γ, and IL-17A and the antiinflammatory IL-10. This evidence concerns the gene IL6 and arthritic joint disease.