Increased mucosal synthesis of rheumatoid factor (RF) in coeliac disease.

Increased serum levels of RF have been reported in patients with gluten sensitivity. The objective of this study was to investigate the in vivo secretion of different isotypes of RF in the small bowel in coeliac disease. Nineteen patients were investigated by perfusion of a defined jejunal segment, and the jejunal perfusion fluid was analysed for the presence of IgA and IgM anti-Fc (IgG). Five of the patients studied had serum IgA deficiency. Patients with partial/subtotal villous atrophy but no IgA deficiency (n = 7) had a four-fold increase of IgM-RF (P < 0.001) and a three-fold increase of IgA-RF (P < 0.001) compared with healthy controls (n = 29). Patients with normal jejunal mucosa but no IgA deficiency (n = 7) had similar IgA-RF and IgM-RF concentrations to healthy controls. Patients with serum IgA deficiency had no IgA-RF detectable in jejunal fluid but the highest IgM-RF concentrations, in particular in active disease. The coeliac patients had serum levels of IgA-RF and IgM-RF within the reference ranges. Jejunal fluid levels of IgA-RF and IgA-anti-gliadin antibodies were significantly correlated (P < 0.001). The data indicate that enhanced jejunal mucosal production of RF occurs above all in active coeliac disease. The findings suggest that the immune response to gluten induces a mucosal RF synthesis.