Studies on host defenses enhanced by endotoxins: a brief review

The findings reported here indicate that toxic reactions to endotoxin do not have to be part of the mechanisms leading to clinically improved status of patients or of experimental animals. It seems to be possible to mobilize the host defenses without the unwanted or dangerous side effects which were encountered during fever therapy. For the demonstration of activated host defenses, several experimental models are available. Non-specific resistance to bacterial infections, to lethal irradiation or to experimental challenge with viable tumors are clear manifestations of enhanced capacity of the endotoxin-treated host to compensate for the induced damage, or to cope with an otherwise overwhelming number of pathogenic cells. Immunopotentiation is obviously one of the contributing factors in some of the above parameters. How these results are applicable to human therapy remains to be seen. Such use of endotoxin derivatives, or better, the mediators of beneficial endotoxic effects, must wait until we learn more about the nature of the alternating positive and negative effects of endotoxin application. The importance of the proper timing of such a therapeutic modality cannot be overemphasized.