Infection of asthmatics with human rhinovirus (HRV) enhances airway eosinophilia and airways hyperreactivity. The current studies were performed to further characterize HRV-induced generation by human bronchial epithelial cells of granulocyte macrophage colony-stimulating factor (GM-CSF), a cytokine that could contribute to airway eosinophilia by increasing the survival and activation of eosinophils, and to determine the effects of the antiviral agent nitric oxide (NO) on HRV-induced GM-CSF production. Maximal levels of messenger RNA (mRNA) for GM-CSF were seen 1 h after HRV infection. Expression was sustained through 24 h and declined by 48 h. GM-CSF protein was detected in cell supernatants by 2 h after infection and reached maximal concentrations by 24 h, with the most rapid rate of production occurring from 2 to 7 h. The NO donor 3-(2-hydroxy-2-nitroso-1-propyl-hydrazino)-1-propanamine (NONOate) inhibited HRV-induced GM-CSF protein production in a time- and dose-dependent fashion. NONOate also inhibited HRV-induced GM-CSF mRNA levels at both times (1 and 4 h) examined. NONOate increased GM-CSF mRNA stability, suggesting that reduced mRNA levels were due to inhibition of transcription. The transcription factor nuclear factor-kappa B was rapidly induced by HRV infection, but was not inhibited by NONOate, implying a role for other transcription factors. Thus, NO may play an important anti-inflammatory role in virally induced exacerbations of diseases such as asthma.