Molecular diversity of secretory IgA anti-DNP antibodies elicited in rat bile.

Dinitrophenylated-type III pneumococcus has been used to induce biliary IgA anti-DNP antibody responses in rats. A solid phase radioimmunoassay was employed to quantitate the biliary IgA anti-DNP antibodies after subcutaneous, i.v., or intragastric immunization. All routes were shown to effectively elicit biliary IgA antibody responses. The microscale sucrose isoelectric focusing technique was employed to assess molecular diversity of the secretory IgA anti-DNP antibodies in bile. Subcutaneous and intragastric immunization resulted in complex antibody spectrotypes whereas i.v. immunization yielded restricted antibody spectrotypes, demonstrating that the route of immunization influenced the molecular diversity of the biliary secretory IgA antibodies. These findings are discussed in terms of mechanisms governing the induction of secretory antibodies.