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Reticuloendothelial system Fc receptor-mediated clearance of IgG-tagged erythrocytes from the circulation of patients with idiopathic ulcerative colitis and chronic liver disease

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Abstract

Immune complexes may be important in the pathogenesis of the liver disease associated with idiopathic ulcerative colitis. In the present study, we documented Fc receptor-mediated clearance by the reticuloendothelial system of immune complex-like material from the systemic circulation of 25 healthy control subjects, 19 patients with ulcerative colitis alone, 9 patients with ulcerative colitis and elevated liver enzyme tests and 8 patients with various other formsof chronic liver disease. Following an intravenous infusion of IgG-tagged 51Cr-labeled autologous erythrocytes, serial blood samples were drawn over a 2-hr period of time, and computer-generated clearance curves were obtained. The time required for clearance of 50% of infused erythrocytes (T1/2) was then calculated. Serum immunoglobulin (IgA, IgG and IgM), complement (C3 and C4) and immune complex-like activity (IgG and IgM types) were also determined. Sixteen of 19 (84%) ulcerative colitis patients and 7 of 8 (88%) chronic liver disease patients had normal clearance T1/2's (when compared to 25 healthy controls). Conversely, only 1 of 9 (11%) ulcerative colitis + chronic liver disease patients demonstrated normal clearance function. Aside from serum IgM levels, the results of serum immunoglobulin, complement and immune complex-like determinations were similar in ulcerative colitis and ulcerative colitis + chronic liver disease patients. Serum IgM levels, however, were significantly decreased in ulcerative colitis patients and increased in ulcerative colitis + chronic liver disease patients (p < 0.001).

These results indicate that the reticuloendothelial system of patients with ulcerative colitis and chronic liver disease is impaired in its ability to clear immune complex-like material from the systemic circulation. This finding tendsto support the hypothesis that immune complexes are of pathogenic importance in the liver disease associated with idiopathic ulcerative colitis.

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