1 A lipopolysaccharide extract of Escherichia coli 026:B6 cells (026:B6(B) endotoxin) was shown to be toxic to normal adult guinea‐pigs.
2 The agent had no action on isolated preparations of ileum and heart taken from normal adult guinea‐pigs.
3 Ileal segments from animals actively immunized against 026:B6(B) endotoxin showed dose‐dependent contractions when exposed to endotoxin. Desensitization phenomena were demonstrated.
4 Reactivity of 026:B6(B) endotoxin was transferred to isolated preparations of ileum and heart from normal animals by passive transfer of immune serum.
5 Tissue responses to 026:B6(B) were associated with release of ileal spasmogen into the bath medium. Mepyramine blocked the effects of this spasmogen at bath concentrations which caused little change in ileal responses to carbachol.
6 It is concluded that E. coli endotoxin can elicit anaphylactic reactions, and that this process may potentiate endotoxin toxicity in sensitized animals. However, endotoxin toxicity in guinea‐pigs does not appear to depend on this kind of allergic process.
DOI: 10.1111/j.1476-5381.1977.tb07510.x
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