The influence of three important cytokines (IL-8, TNF-alpha, and HuIFN-alpha) on ongoing rhinovirus infections has been examined in vitro, individually or as combinations. TNF-alpha was able to transform traces of HRV infections into full-blown infections. Furthermore, TNF-alpha was able to down-regulate the antiviral action of HuIFN-alpha completely, even at levels of just a few pg/ml. This suggests that the induction of TNF-alpha by HRV may be part of the virus\'s strategy to minimize the interferon response which is part of the host\'s immune defence system. However, troxerutin (a flavonoid) was able to neutralize the downregulatory action of TNF-alpha on the HuIFN-alpha system at low levels and re-establish the antiviral activity ascribed to IFN-alpha. IL-8 exerted a minor influence on the interferon system, and had no influence on rhinovirus infections. The in vitro findings are supported, in part, by recent in vivo findings in a common cold pilot study.