Immunology of peripheral nerves and response to trauma

Research in limb reconstruction using peripheral nerve tissue has been hampered by tissue rejection. In order to provide more information on the immunology of peripheral nerves, 35 specimens (26 from seven cadavers and nine from surgical biopsies) were analyzed for the presence of human leukocyte antigens (HLA), which are a key component of major histocompatibility complex class II (MHC Class II) antigens. MHC Class II antigens were noted in all human nerve specimens, and the percentage of areas of positive staining by immunohistochemistry was significantly higher (3.82% +/- 1.01%) than that of negative controls (.05% +/- 0.02%) (p less than 0.01). The negative controls consisted of serial sections that were stained in the same manner except that the primary antibody was deleted. There was no significant difference in the presence of MHC Class II antigens between sensory and mixed motor nerves or among the different HLA groups (HLA-DR, HLA-DP, HLA-DQ). A mouse model was used to evaluate the effect of trauma on the presence of MHC Class II antigens. Three weeks after transsection of the sciatic nerve there was a statistically significant increase (p less than 0.05) in the presence of MHC Class II antigens in the distal portion of the nerve (4.49% +/- 0.78%) as compared with samples from animals that had had exposure of the nerve without transsection (1.44% +/- 0.21%) or in nerves from animals that had had no surgery (1.02% +/- 0.21%). The presence of MHC Class II antigens could require more complex cross-matching for tissue transplantation. Nerve grafts that have undergone Wallerian degeneration may actually be more prone to rejection than are other peripheral nerve tissue transplants.