Cyclophosphamide-sensitive and cyclophosphamide-resistant suppressor cells in the immune response to alloantigens.

We have demonstrated that within a given system Cy may alter the immune response in different ways. It may augment the response by inactivating CSS cells or induce immunosuppression by activating CRS. Furthermore, our studies provide a means of analyzing the mechanism of suppression, that is, delineating the target cell for suppression, the properties and life span of the suppressed cells, and the nature of the cell interactions involved. Furthermore, with the available information on the immunosuppressive activity of Cy, clinical studies may be best monitored in transplantation immunology and tumor chemotherapy. It is possible that the induction of CRS cells, which are antigen-nonspecific and non-H-2-restricted, may be useful for inducing specific immunosuppression to alleviate GVH reactions. These studies are currently in progress.