Role of viruses in the onset of asthma and allergy: lessons from animal models

The primary role of the immune system is to protect the host against pathogens. Until recently it has been thought that the immune system functioned in isolation, however, it has become increasingly evident that the immune system and, in particular, the nervous system are functionally interconnected. In this review we describe various interactions between the nervous and immune systems in the lung. Particular attention will be given to the interactions of neuropeptide mediators from the nonadrenergic, non-cholinergic (NANC) sensory nervous system with mast cells, macrophages and cosinophils, and the special role that nerve growth faclor (NGF) plays in these interactions.