Effect of Salmonella Endotoxins on Lymphocyte Cultures Grown in the Ecoanalyzer

Two distinct endotoxins are produced by Salmonella typhimurium, one at pH 7.0 and the other at pH 4.2, as determined by gel precipitin reactions and by biochemical analyses. pH 4.2 endotoxin lacks heptose that is present in pH 7.0 endotoxin, and the 2-keto-3-deoxyoctonate moiety of endotoxin has been modified in a fashion that causes displacement of the usual absorption peak for this structure. The pH 4.2 endotoxin is much less toxic for mice than is the pH 7.0 endotoxin. Under tissue cell culture conditions, swine buffy coat cells and human lymphocyte RPMI 1788 cell line cells showed cytopathic effects from 5 microgramml endotoxin in the culture medium. pH 7.0 endotoxin was clearly more toxic at this dose level than was pH 4.2 endotoxin, as pH 7.0 endotoxin was lethal to exposed lymphocytes, at 48 hours, at which time 4.2 endotoxin showed only slight cytopathic effects on the cells.