STUDIES ON THE BIOLOGIC RELATIONSHIP OF ENDOTOXIN AND OTHER TOXIC PROTEINS

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Abstract
Scattered evidence has suggested that host resistance mechanisms to Agkistrodon piscivorus venom and gram-negative endotoxins are interrelated. Present studies show that prior injection of venom does not protect rabbits against the local or general Shwartzman reaction, contrary to an early report, but refractoriness to endotoxin (induced by a course of endotoxin injections) is paralleled by low grade resistance to snake venom (given at least 7 days after last endotoxin) in mice, confirming earlier work, and in rabbits. A single intradermal or intravenous injection of endotoxin increased susceptibility of rabbits to sublethal doses of venom administered 18-24 hours later. No immunologic cross-reactivity of the endotoxin and venom could be demonstrated. Other studies had also suggested that endotoxin and venom share some biologic properties. This study showed that these 2 toxins differ in effects on: immune response to simple protein antigen, body temperature, circulating leukocyte count, and capacity to prepare for and provoke the local and general Shwartzman reaction. Serial intravenous injections of sublethal doses of venom produced enhanced susceptibility to venom rather than refractoriness. Zymosan failed to enhance susceptibility to venom, but thorotrast increased the number of late deaths from venom. Exposure of venom to ferrous sulfate interfered with its toxicity.