Immunity to experimental cholera. I. Protective effect of humoral IgG antitoxin demonstrated by passive immunization

The protective role of serum IgG antitoxin was studied in dogs transfused either with whole plasma or purified serum IgG from hyperimmunized dogs. Washings of jejunal Thiry Vella loops after plasma transfusion yielded IgG antitoxin. Furthermore, dogs transfused with antitoxic plasma were protected against intrajejunal challenge with cholera toxin and this protection could not be diminished by extensive washing of the jejunum prior to toxin challenge. Finally, intact dogs transfused with antitoxic serum IgG were highly protected against orogastric challenge with viable Vibrio cholerae. These results indicate that serum IgG can play a protective role at the surface of the gut mucosa or within its lumen. They also suggest that serum derived antibody may exert its effect while intimately associated with the mucosa, a position in which it may be protected from lipid destruction by proteolytic enzymes.