Occurrence of Specific Antibodies of the IgA Class in the Bile of Rats

Abstract
In pooled bile, obtained by cannulating the common bile duct of normal rats, the immunoglobulins were mainly of the IgA class but the total immunoglobulin concentration was 20 times less than in the blood. Paired samples of blood serum and bile were collected from rats at various times after antigens had been injected into the Peyer’s patches, the spleen, or the subcuticulum. Between 5 and 10 days after killed bacteria had been injected into the Peyer’s patches, specific agglutinins appeared in the bile in titres that often were as high as those in the blood, and much higher than those in the bile of rats that had been immunized by other routes. By using specifically purified, radiolabelled antiglobulin reagents it was shown that the antibodies in the bile were mainly of the IgA class, whilst those in the blood were of the IgG and IgM classes. A similar distribution of antibody isotypes was found after allogeneic white cells had been injected. Substantial amounts of alloantibodies of the IgA class were found in the bile but not in the blood; in addition, the bile contained significant amounts of antibody associated with IgM. Thus, by injecting antigens into Peyer’s patches and collecting the bile it is easy to obtain specific, secretory antibodies in the amounts needed for the investigation of their functions in vitro and in vivo.