Induction and distribution of intestinal immune responses after administration of recombinant cholera toxin B subunit in the ileal pouches of colectomized patients

The induction and dissemination of mucosal immune responses to recombinant cholera toxin B subunit (rCTB) administered into the ileal pouches of patie nts, who had been colectomized because of ulcerative colitis, was analyzed. Biopsies from the duodenum and ileal pouch were collected, along with peri pheral blood and ileostomy fluids. Two immunizations induced strong CTB-spe cific immunoglobulin A (IgA) antibody-secreting cell (ASC) responses in the duodenum in five of fire patients, whereas weaker and less-frequent ASC re sponses were noted in the ileal pouch. Intestine derived CTB-specific IgA A SCs were found in peripheral blood in three of the five patients. The vacci nation also induced significant IgA antitoxin titer rises in ileostomy flui d in all of the patients. Increased production elf gamma interferon in cell cultures from the ileal pouch was found in four of fire patients after the vaccination. These results clearly indicate that rCTB administered into th e distal ileum is capable of inducing B-cell responses in the "entire" smal l intestine and that homing of immunocompetent cells occurs preferentially to the duodenum.