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 extended^6–9. 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.