Immune responses of rats to live Vibrio cholerae: secretion of antibodies in bile.

Agglutinating and vibriocidal antibodies appear in the bile of rats within a few days of intravenous or intraintestinal injection of live Vibrio cholerae. Whereas the presence of IgM and IgG antibodies area accounted for by passive exudation from serum., those of the IgA class are selectively (actively) transferred from serum to bile. Bile duct ligation causes a 10-fold increase in serum IgA levels over a 48-h period; a similar increase in agglutinating antibody titre occurs only in rats injected intraintestinally, thus providing further evidence for the predominance of IgA-antibody formation when antigen is taken up from the intestinal lumen. Biliary antibodies do not appear to augment the antibody levels in mucus secretions that adhere to the small intestine surfaces. However, when the bile flow is interrupted by bile duct occlusion or cannulation, the antibody levels in these secretions increase in parenterally-immunized animals. It is unlikely, therefore, that bile duct ligation will provide a satisfactory approach to determining the protective function of biliary V. cholerae antibody.