ABSTRACT

The implication of tumor necrosis factor (TNF) and macrophages in directed against endotoxin (LPS)-induced tumor regression has shifted much of the interest in endotoxin and cancer to the study of mediators such as TNF. Endotoxin is a potent activator of host defense, and it has even been suggested that LPS may be necessary to maintain a viable immune system. Proportional mortality ratio is lower for occupations involving exposure to grain and wood dust, which is high in LPS, but the PMR in groups exposed to plywood dust is higher than normal. The potential importance of endotoxin in reducing cancer risk has also been demonstrated in animal experiments, because lower tumor frequency has been observed in animals exposed to endotoxin or cotton dust by inhalation. Through evolution, mammals have developed extremely sensitive mechanisms for recognizing endotoxin. The biological actions of IL-1 can be blocked by infusion of the naturally occurring IL-1ra.