Suppression of specific MLC responsiveness during skin allograft rejection in rats.

During the effector phase of allograft rejection a specific MLC unresponsiveness of PBL has been observed in skin-grafted rats. This unresponsiveness is caused by a suppressive effect that is dependent on a cooperative interaction between macrophages and alloantigen-activated T cells. The interaction is mediated by a soluble factor released from the alloantigen-activated T cells on exposure to the specific antigen. The suppression itself is nonspecific.