In vitro immunoglobulin secretion by normal human gastrointestinal mucosal tissues, and alterations in patients with inflammatory bowel disease.

Intestinal mucosal immunoglobulin secretion in vitro has been studied by culture of endoscopic biopsy tissues obtained from various sites along the gastrointestinal tract. IgA and IgM were the predominant immunoglobulins produced by intestinal tissues distal to the stomach and secretion of both reached a maximum in the small intestine of normal individuals. In patients with inflammatory bowel disease, characteristic alterations in immunoglobulin production were observed in cultures of large intestinal tissue. In ulcerative colitis (UC), significant reductions in IgA secretion (P less than 0.03) occurred in the rectum during remission and IgM in the colon in active disease (P less than 0.01). However, in active Crohn's disease (CD), rectal IgM secretion was enhanced (P less than 0.004) and IgA diminished (P less than 0.01). IgG secretion was increased throughout the colon in UC especially in distal sites, due largely to significant increases in pre-formed immunoglobulin (P less than 0.02). Similar total increases were observed in colonic tissues from patients with CD, although IgG synthesis in biopsies from rectal sites was normal. These findings suggest that specific abnormalities of intestinal mucosal immunoglobulin synthesis occur in patients with both UC and CD.