CX3CL1 and asthma: Following our interesting observations for RV16-induced release of fractalkine by BAL cells and PBMCs were generated from in vitro RV infection experiments, we also measured levels of fractalkine in BAL fluid from a separate study [11] to investigate whether in vivo RV16 infection increases levels of fractalkine locally in the bronchial mucosa, an important site for RV infection in asthma.