We infected 7 normal volunteers with rhinovirus 16. In general, the symptoms and alterations in airways were minimal although all subjects had upper respiratory symptoms. Three subjects developed in addition lower respiratory and systemic symptoms accompanied by either an increase in the volume of isoflow or a positive methacholine response. Furthermore, these three had a decrease in beta adrenergic and H2 histamine receptor responses of their granulocytes. Since the peripheral airway obstruction and decreased beta adrenergic and H2 histamine responses occurred together, these two phenomenon may have a common cause. All seven subjects had a decrease in number of circulating E rosette-forming lymphocytes, and in 6 of 7, there was a decrease in the antibody-dependent cellular cytotoxicity capacity of mononuclear cell preparations. It is not clear whether these changes reflect redistribution of mononuclear cells or alteration of their function.