Intestinal stimulation of the serum antibody response against Escherichia coli O83 antigen in healthy adults.

Ingestion of E. coli O83 bacteria preceded by intake of 2 g of NaHCO3 resulted in the bacteria appearing as a transient strain in the stool in 6 out of 11 healthy adult individuals. No rise in serum, urine or parotid fluid antibody levels against the crude O antigen from E. coli O83 bacteria could be detected using the enzyme-linked immunosorbent assay (ELISA) or the indirect haemagglutination (IHA) technique. In contrast, a serum antibody response was registered in four individuals with the ammonium sulphate precipitation (ASP) technique. The rise in antibody level was accompanied by an increase in relative average antibody avidity. Significantly lower levels of serum antibodies against the E. coli O83 and O6 antigens were recorded using the ASP technique as compared to those for O2, O4 and O75 antigens.