Escherichia coli heat-labile enterotoxin: comparison of antitoxin assays and serum antitoxin levels.

The mouse adrenal tumor cells (Y-1 strain) and the Chinese hamster ovary cells, two routinely used tissue culture assays for Escherichia coli heat-labile enterotoxin (LT), were used to detect serum antitoxin responses in culture-positive patients from several well-defined sources. There was no correlation between a significant antitoxin response and isolation of LT-producing E. coli in two "domestic" diarrheal outbreaks. Serum samples from a third group of individuals in a rural cholera-endemic area consistently demonstrated significant rises in neutralizing antibody to LT.