Endotoxin tolerance in rats treated with antilymphocyte serum.

Rats were treated with rabbit anti-rat lymphocyte serum (ALS). The subsequent selective immunosuppressive effect on the immune response of thymus dependent antigen was shown by immunization with sheep red blood cells (SRBC). Endotoxin tolerance could be evoked in ALS treated animals. This suggests that the establishment of endotoxin tolerance is independent of thymus function and makes it possible to enhance the nonspecific resistance of immunosuppressed patients with a transplanted organ.