Effects of parenteral keyhole limpet hemocyanin or cholera toxin on intestinal immune response to keyhole limpet hemocyanin

This study evaluated whether subcutaneous priming with either keyhole limpet hemocyanin (KLH), a protein antigen lacking toxic properties, or cholera toxin (CT), whose toxic activity is known to modulate immune responses, would enhance or suppress the local intestinal IgA response to KLH. In rabbits given KLH into chronically isolated ileal loops, subcutaneous priming and boosting with the same antigen resulted in increased serum and loop fluid IgG anti-KLH, but loop fluid IgA anti-KLH was not statistically significantly different from controls. With subcutaneous administration of CT, loop fluid IgA anti-KLH and serum IgG anti-KLH showed a suggestion of an earlier rise than in controls, but were not significantly different. The failure of subcutaneous KLH or CT to enhance local intestinal IgA immune response to KLH indicated that the feasibility of parenteral priming must be determined individually for each antigen to which intestinal immunity is desired.