Water extract of deer antler aqua-acupunture (DAA) prepared from the growing antler of Cervus korean TEMMINCK var. mantchuricus Swinhoe, was used to investigate the efficacy of a traditional immunosuppressive and immuno-activating Korean aqua-acupuncture, on the development of type II collagen (CII)-induced arthritis (CIA) in rats. The onset of arthritis was observed at the 24th day after the CII-immunization in rats, and the severity of CIA was gradually developed. As compared with rats treated with saline, DAA i.p. injected at doses of more than 50 microg/kg once a day for 14 days inhibited the ability of inguinal lymph node cells to produce T cell cytokines interleukin 2 and interferon-gamma when the cells were obtained from rats 24 days after immunization and cultured in vitro with CII. Treatment with DAA also inhibited the production of macrophage cytokines interleukin-1beta, IL-6 and tumor necrosis factor alpha in response to in vitro stimulation of lymph node and macrophage cells with CII. In addition, in order to evaluate the influence of DAA on the incidence and development of arthritis in rat CIA, rats were immunized twice at a 3-week interval with bovine CII, with DAA being given i.p. once a day for 14 days with four different regimens. A 14-day course of DAA treatment at a daily dose of 100 microg/kg, which began on the day of the first CII immunization, suppressed the development of arthritis, as well as antibody formation and delayed-type hypersensitivity to CII. Treatment with DAA, which started on the same day as the booster immunization, also resulted in inhibition of development of arthritis and of immune responses to CII. However, treatment with DAA, which was prophylactically started prior to a primary immunization, did not inhibit the development of arthritis and immune response to CII. Furthermore, DAA extract did not affect the established diseases.