Role of Bacterial Endotoxin in the Graft-vs.-Host Syndrome

Abstract

A comparison of the histopathology and the general macroscopic features of the graft-vs.-host reaction (GVHR) with those produced by bacterial endotoxin suggests an important role of bacterial endotoxicity in the GVHR and related experimental models for immune-deficiency states. The protective effect of antibiotic therapy and the lack of development of a lethal syndrome in germfree animals undergoing the GVHR or after thymectomy further supports the importance of endotoxemia in these syndromes. It is proposed that bacterial endotoxicity may influence immune senescence and lead to the increasing incidence of disease and cancer that occurs with age; this phenomenon may also explain some of the complications presently associated with immune suppression and lymphoid transplantation in man.