OBJECTIVE:To measure gut immunity directly in jejunal fluid in patients with ankylosing spondylitis (AS) and rheumatoid arthritis (RA). METHODS:Antibodies against three different Enterobacterias were measured in jejunal perfusion fluids (collected by a double balloon perfusion device) of 19 patients with AS, 14 patients with RA, and 22 healthy controls using enzyme linked immunosorbent assay. RESULTS:The AS patients had significantly increased jejunal fluid concentrations of IgM, IgG, and IgA class antibodies against Klebsiella pneumoniae, and IgM and IgA class antibodies against Escherichia coli and Proteus mirabilis compared with healthy controls. When compared with the patients with RA, the AS patients had higher concentrations of IgA and IgG class antibodies only against K pneumoniae. The RA patients had higher IgM class antibody concentrations against all three studied Enterobacterias, when compared with the healthy controls, suggesting an enhanced mucosal immune response in these patients. A three month treatment with sulphasalazine did not decrease enterobacterial antibody concentrations in the 10 patients with AS. CONCLUSION:There is strong direct evidence for an abnormal mucosal humoral immune response particularly to K pneumoniae in patients with AS.

The small intestines of healthy volunteers were challenged with ethanol during regional perfusion of a defined jejunal segment. Infusion of 30 mL of 5000 mmol/L ethanol to the perfused jejunal segment gave a maximum ethanol concentration of 973 +/- 98 (SEM) mmol/L in the jejunum lumen. This ethanol challenge induced within 20-30 minutes a 10-fold increase in albumin (P less than 0.001) and a two-fold increase in the glycosaminoglycan hyaluronic acid (P less than 0.05) in the perfusion fluid. Later during the challenge and simultaneously with a decreased jejunal loss of albumin, the jejunal recovery of prostaglandin E2 increased fourfold (P less than 0.01). The jejunal fluid concentrations of histamine and eosinophil cationic protein remained stable during the ethanol challenge. No changes in the jejunal appearance of albumin or other measured substances were seen when the maximum jejunal fluid concentrations of ethanol were less than 400 mmol/L achieved during challenge with smaller amounts of ethanol. The increased jejunal fluid appearance of hyaluronic acid after ethanol challenge indicates increased leakage from the interstitial/lymph fluid of the gut wall due to altered mucosal permeability. The relatively larger jejunal losses of albumin suggest that ethanol induces increased microvascular permeability of the jejunum as well.