Background: Hormone substitution for the treatment of adrenocortical insufficiency (Addison's disease) does not adequately substitute the hormone peaks required in stress situations. Therefore, allogeneic transplantation of adrenal cortex could offer an intriguing alternative.
Methods: Major histocompatibility complex (MHC) class I transgenic mice were used for the implementation of an animal model of adrenocortical cell transplantation in adrenalectomized mice. K(b)-transgenic cells and allogeneic adrenocortical cells were cocultured in mixed lymphocyte cultures to examine the alloimmune response. Lymphocytes from T-cell receptor transgenic mice and normal allogeneic mice served as responder cells. The effect of corticosteroids secreted by adrenocortical cells was antagonized by the steroid receptor antagonist mifepristone (RU486).
Results: In vitro coculture experiments showed that MHC class I disparate adrenocortical cells failed to activate B10.BR and T-cell receptor transgenic lymph node cells. In the presence of mifepristone this inhibitory effect was antagonized, resulting in strong lymphocyte proliferation. Activation of B10.BR lymphocytes by K(b)-disparate spleen cells was also abolished in the presence of adrenocortical cells. This effect, however, could not be reversed by mifepristone.
Conclusions: In vitro, the presence of adrenocortical cells potently suppressed allogeneic immune responses. This effect was only in part due to the secretion of corticosteroids, pointing to an additional immunomodulatory property of adrenocortical cells.