The use of herbal and other botanical products, including those used extensively in traditional Chinese medicine, has increased dramatically in the last decade. Yet, little scientific research exists concerning their efficacy and safety. We examined the effects of Immune+, a combination of five botanicals frequently used in traditional Chinese medicine, on the production of two cytokines. For this purpose, unstimulated or phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells from healthy volunteers were incubated with different concentrations of Immune+. The secretion of interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma) was measured after 72 hours of incubation. At the highest concentration tested (100 micro g/ml), Immune+ significantly increased the secretion of IL-1beta. Importantly, PHA alone had no effect on IL-1beta production, and the combination of PHA with Immune+ resulted in the same increase in IL-1beta production as seen with the botanical extract alone. Immune+ did not have any detectable effect on either unstimulated or PHA-stimulated IFN-gamma synthesis. These in vitro data support the concept that Immune+ may enhance human immune responses.