Neuropeptides, nerve growth factor, and mucosal immunity

Since the discovery more than 20 years ago that IgA in its secretory form of dimeric IgA covalently linked with the glycoprotein, secretory component (SC), the predominant immunoglobulin in external secretions, the emphasis has been on this molecule as a prime mediator of mucosal immunity. While there is no doubt that IgA is an important effector molecule, there is increasing evidence that often it may be only a marker of an effective mucosal response and that other mechanisms are involved in inducing mucosal resistance.