Antigenic stimulation with proteins of cow's milk via the oral route in guinea pigs and rats. 2. Antibodies to beta-lactoglobulin secreted into the alimentary canal and serum.
The intestinal contents of guinea pigs and rats on a milk-drinking diet were examined for mucosal-secreted antibody to beta-lactoglobulin. Assay of the immunoglobulin content of duodenum, jejunum and ileum of the guinea pig gave geometric means of 70, 90 and 95 micrograms/ml. In the rat, where isotype-specific antiglobulin reagents were available, similar figures were obtained but it could be shown that the vast majority was IgA. Passive haemagglutination titres up to 1,000 of secreted anti-beta-lactoglobulin antibody (resistant to the endogenous proteases in the intestinal contents) were measured in guinea pigs. Fifteen days after cessation of milk-drinking, the antibody had dropped to undetectable levels. No such antibody could be shown in rats. Rats also failed to develop detectable serum antibody whereas, the guinea pigs had passive haemagglutination titres in the order of 16,000.