Elevated serum IgA associated with immunoproliferative enteropathy of Basenji dogs: lack of evidence for alpha heavy-chain disease or enhanced intestinal IgA secretion.

Immunoglobulin isotypes in serum and intestinal secretions of Basenji dogs with chronic diarrhea, asymptomatic Basenji dogs, and healthy control dogs were quantitated and their molecular sizes characterized to detect alpha-chain, gamma-chain, or mu-chain fragments. Quantitation of immunoglobulin isotypes in serum showed that affected Basenjis have significantly elevated serum IgA values as compared to asymptomatic Basenjis and normal control dogs. However, IgA concentrations in intestinal wash fluids were not significantly different for the three groups. Immunoelectrophoresis (IEP) and polyacrylamide gel electrophoresis (PAGE) demonstrated that virtually all IgA was in the dimeric form. Using IEP and immunoselection, we were unable to detect evidence for the presence of alpha-chain or other heavy-(H)-chain fragments. Hyperimmune serum obtained from rabbits immunized with serum or a globulin fraction of affected Basenjis also failed to detect H-chain fragments. The results of this study indicate that immunoproliferative enteropathy of Basenjis resembles closely the nonsecretory form of human immunoproliferative small intestinal disease (IPSID).