IMMUNOLOGICAL REACTIONS FOLLOWING INTRACEREBROVENTRICULAR TRANSPLANTATION OF ADRENAL-MEDULLA

Immunological reactions after intracerebroventricular syn-, allo- and xenogenic transplantation of adrenal medulla were investigated histolo gically. In xenografts only, T cell infiltration and graft rejection w ere observed. Syngrafts and allografts were not rejected and were not infiltrated by T cells, although expression of MHC class II antigen wa s observed at all survival times. Major histocompatibility complex (MH C) class I immunoreactivity was strongly expressed in adrenal cortex s yngrafts, which could play a role in the rejection of grafts containin g mixed cell populations. The survival of chromaffin cells in allograf ts was decreased as compared to syngrafts, and there were fewer allogr aft animals with large numbers of surviving chromaffin cells. There wa s some increased cellularity (microglia and macrophages) in allografts even though no T cell infiltration was found. Therefore, it appears t hat this limited survival of intracerebral adrenal medulla allografts is not due to T cell-mediated graft rejection.