Acupuncture regulates natural killer cells in women Electro-acupuncture stimulation (voltage intensity, 1 to 5 V; duration, 1 ms; frequency, 1 Hz) was applied to bilateral ST36 acupoints once a day (1 h) for 3 d. NK cytotoxicity was measured by the standard 4-h 51Cr release assay. Successive acupuncture treatment for 3 d significantly enhanced splenic NK cytotoxicity (p 0.001) on the first day after final treatment as compared to that of the control. However, similar stimulation to abdominal muscle did not influence splenic NK cytotoxicity. We also examined endogenous cytokine activities in aqueous spleen extracts prepared from acupunctured and control rats. The extracts from rats acupunctured at the ST36 acupoint contained high levels of interleukin (IL)-2 and interferon (IFN)-gamma as compared to those of abdominal muscle acupunctured and non-acupunctured control rats (p 0.01). Furthermore,a significant positive correlation (p 0.01) was observed between the levels of each cytokine tested and splenic NK cytotoxicity. The same positive correlation was also observed between the levels of IL-2 and IFN-gamma (p 0.01). These observations indicate that electro-acupuncture stimulation of the ST36 acupoint enhances splenic NK cytotoxicity and that IL-2 and IFN-gamma may function, at least in part, in the regulation of NK cell activity in this system. Reference Yu, et al. (1997) Enhancement of splenic interferon-gamma, interleukin-2, and NK cytotoxicity by S36 acupoint acupuncture in F344 rats. Jpn J Physiol; 47(2): 173-8.