LUMINAL ANTIGLIADIN ANTIBODIES IN SMALL-INTESTINAL BACTERIAL OVERGROWTH

Objective: Elevated antigliadin antibody levels in small intestinal lu minal secretions of subjects with normal or only mildly abnormal small intestinal histology are considered indicative of ''latent'' or ''pot ential'' celiac disease. The purpose of this study was to determine wh ether small intestinal bacterial overgrowth (SIBO) might provide an al ternative explanation for positive luminal antigliadin antibodies in s uch subjects. Methods: Twenty-six adult subjects without predispositio n to disturbed mucosal immunity were investigated with culture of smal l intestinal luminal secretions. Luminal total IgA and IgA-antigliadin antibody concentrations were measured by radial immunodiffusion and i ndirect enzyme immunoassay, respectively. Local mucosal counts of IgA- plasma cells were determined by immunohistochemistry. Small intestinal histology and intraepithelial lymphocyte counts were assessed by ligh t microscopy. Corresponding serum antigliadin antibody concentrations were determined. Results: SIBO was present in 17/26 (65.4%) subjects. No subject with SIBO had villous atrophy. Luminal total IgA concentrat ions (p < 0.0005), mucosal IgA-plasma cell counts (p < 0.01), and intr aepithelial lymphocyte counts (p < 0.01) were significantly increased in subjects with SIBO. Luminal IgA-antigliadin antibodies were detecte d in 6/17 (35.3%) subjects with SIBO and 0/9 (0%) subjects without SIB O. Luminal IgA-antigliadin antibody concentrations correlated signific antly with luminal total IgA levels (p < 0.01) but not with serum valu es (p < 0.1). Serum IgG-antigliadin antibody concentrations were eleva ted in 2/6 (33.3%) subjects with SIBO and positive luminal antigliadin antibodies. Conclusions: SIBO may be an alternative explanation to '' latent'' or ''potential'' celiac disease for positive luminal antiglia din antibodies in subjects with either normal or only mildly abnormal small intestinal histology, even when serum antigliadin antibody conce ntrations are elevated. Positive luminal antigliadin antibodies in SIB O probably occur as epiphenomena in the context of a graded mucosal im mune response to local bacterial antigens.