Avidity of cholera antibody

Abstract IgA, IgA, and IgM of the serum and intestinal wall of chimpanzees, and of human serum, were studied after antigenic stimulation with cholera toxin. Antibody avidity at various pH values was determined. The cholera toxin neutralizing and the haemagglutinating capability of the native Ig-s as well as the Ig-s liberated from antibody-antigen complexes were investigated. The avidity of IgM and non-secretory IgA increased, whereas that of IgG and secretory (intestinal) IgA did no change essentially during 14 days following antigenic stimulation. Relatively large amounts of toxin were bound by IgG and secretory IgA. The haemagglutination titres increased but did not parallel antitoxin formation and Ig-antiboty avidity in the intestinal tissue. The need for antitoxin studies in persons exposed to cholera was emphasized.