The PNS is an immunocompetent organ. The participating cellular and humoral elements in the local immune circuitry have been identified. The model disorder EAN is extensively being used to examine the induction, amplification and effector phase of autoimmune responses to peripheral nerve antigens (Figure 9). Potential autoantigens contained in the myelin sheath and on the axolemma have been characterized. Recent years have seen a rapid growth of information concerning the pathogenesis of the Guillain-Barré syndrome, which has turned out to be a heterogeneous disorder, both in clinical characteristics, course and prognosis, and in the underlying pathology. It can be anticipated that using the better understanding of principal mechanisms of autoimmunity in the PNS will aid in the development of more specific and efficacious treatments.