Placental secreted factors: Their role in the regulation of anti-CII antibodies and amelioration of collagen induced arthritis in rats

Pregnancy induces collagen-induced arthritis (CIA) remission in rats. Placental hormones, cytokines and growth factors can regulate immune cell activity at the feto–maternal interface as well as at the systemic level. We assessed the effect of placental culture supernatants (PS) in CIA developed in rats after the inoculation of collagen type II (CII) in complete Freund's adjuvant. After the onset of CIA, animals were injected by ip route with seven doses of PS. On the 18th day of treatment with PS, serum anti-CII antibody (total IgG, IgG1, IgG2a, IgG2b, IgG asymmetric molecules) and cytokine levels were determined by ELISA. An arthritic index was used by daily measure of joint swelling and visual signs of arthritis.Our results demonstrated that the PS treatment diminished CIA symptoms, reduced TNF-α, INF-γ and anti-CII antibody serum levels, increased the proportion of asymmetric IgG anti-CII antibodies and affected IgG1/IgG2a and IgG1/IgG2b ratio. Two weeks after the last PS inoculation there was a recurrence of arthritis, a rise in IgG anti-CII and, simultaneously, the percentage of asymmetric IgG anti-CII fell. We concluded that PS have an effective CIA suppressor activity partly due to the modulation of humoral immune response and may be closely related to an inhibitory effect on TNF-α and INF-γ production.