Immunologists getting nervous: neuropeptides, dendritic cells and T cell activation

It is increasingly recognised that the immune and nervous systems are close ly integrated to optimise defence systems within the lung. In this commenta ry, the contribution of various neuropeptides such as substance P, calciton in gene-related peptide, vasoactive intestinal peptide and somatostatin to the regulation of T cell activation is discussed. These neuropeptides are r eleased not only from nerve endings but also from inflammatory immune cells such as monocytes, dendritic cells, eosinophils and mast cells. On release they can exert both direct stimulatory and inhibitory effects on T cell ac tivation and also indirect effects through their influence on the recruitme nt and activation of professional antigen-presenting dendritic cells. Neuro peptides should therefore be included in the conceptual framework of the im mune regulation of T cell function by dendritic cells.