Although anticholinergics inhibit bronchoconstriction in asthmatics and antigen challenged animals, administration of atropine 1h prior to antigen challenge significantly potentiates airway hyperreactivity and eosinophil activation measured 24h later. This potentiation in airway hyperreactivity is related to increased eosinophil activation and is mediated at the level of the airway nerves. Since eosinophils produce nerve growth factor (NGF), which is known to play a role in antigen-induced airway hyperreactivity, we tested whether NGF mediates atropine-enhanced, antigen challenge-induced hyperreactivity. Antibody to NGF (Ab NGF) was administered to sensitized guinea pigs with and without atropine pretreatment (1 mg/kg; iv) 1h before challenge. Twenty-four hours after challenge, animals were anesthetized, vagotomized, paralyzed and ventilated. Electrical stimulation of both vagus nerves caused bronchoconstriction that was increased in challenged animals. Atropine pretreatment potentiated antigen challenge-induced hyperreactivity. Ab NGF did not alter eosinophils or inflammatory cells in any group, nor did it prevent hyperreactivity in challenged animals that did not receive atropine. However, Ab NGF did prevent atropine-enhanced, antigen challenge-induced hyperreactivity and eosinophil activation (assessed by immunohistochemistry). This effect was specific to NGF since animals given control IgG remained hyperreactive. These data suggest that anticholinergics amplify eosinophil interactions with airway nerves via NGF. Therefore, therapeutic strategies that target both eosinophil activation and NGF mediated inflammatory processes in allergic asthma are likely to be beneficial.