Detection and characterization of circulating immune complexes in peptic ulcer

Immunological factors have been implicated in the pathogenesis of peptic ulcer following the demonstration of autoantibodies against IgA in patients with this disease. We investigated whether circulating immune complexes were present in this condition, and what type of immunoglobulins were involved.

The sera of 37 patients with duodenal ulcer and 8 with gastric ulcer were tested for the presence of circulating immune complexes using the polyethylene glycol (PEG) assay and the results compared with those in 79 controls. The precipitate was dissociated and the levels of IgA, IgG and IgM estimated using the single radial immunodiffusion technique. Simultaneous estimation of these immunoglobulins in the serum was also done. Autoantibodies against IgA in the serum were tested using the ELISA test.

Eleven patients (6 with duodenal ulcer and 5 with gastric ulcer) were found to have circulating immune complexes. The mean protein content of the PEG precipitates was significantly higher in patients than in control subjects (p < 0.001). The mean values of all the immunoglobulin isotypes were higher in patients than in controls. The IgA content in the PEG precipitates of positive cases was higher than that in control subjects (p < 0.05).

Patients with peptic ulcer have circulating immune complexes which may interfere with normal immunoregulation.