Letter: Immunosuppressive properties of the lymphocyte chalone.

Abstract

EXPERIMENTAL evidence indicates that a number of cells are mitotically controlled by specific and endogenous negative feedback inhibitors of mitosis called “chalones”1–3. Moor-head et al.4 were the first to apply this concept of a negative feedback inhibitor of mitosis to the lymphocyte system. They demonstrated that extracts of pig lymph node contained material which would inhibit the transformation of PHA-stimulated human lymphocytes in culture and the in vitro mitotic activity of lymphocytes derived from patients with lymphocytic leukaemia5. These observations have been confirmed and extended6–9. Because of the importance of lymphocyte transformation to the phenomenon of graft rejection, Garcia-Giralt et al.10 and Kiger et al.11–13 demonstrated that extracts of lymphoid tissue could partially inhibit both graft-versus-host and allograft rejection in mice. Here we describe the concentration and partial purification of lymphocyte chalone and its application to immunosuppression in both in vitro model systems and in vivo studies of mouse skin allograft rejection.