Expression of Schwann cell and peripheral T-cell activation epitopes in hereditary motor and sensory neuropathy

To evaluate possible immune-mediated mechanisms in hereditary motor and sensory neuropathy (HMSN-I, Charcot-Marie-Tooth syndrome), we examined class II major histocompatibility complex antigen expression (MHC-II, HLA-DR) in Schwann cells and peripheral lymphocyte T-cell (Ta1, CD26) activation in five unrelated adults with HMSN-I. Evidence of increased activation expression was found in both compartments but the pattern did not suggest a general state of hyperimmunity or appear related to clinical characteristics of HMSN. Significantly increased CD26+ T-cell activation and greater than normal fluctuation of values occurred intermittently in sequential tests of eight HMSN patients and at single time points in 24 others. The combined data, consistent with repeated stimulations of an immune reaction under normal feedback control, suggest that HMSN-I expresses some characteristics also found in autoimmune polyneuropathies.