The authors describe the development of a double antibody radioimmunoassay specific for human secretory IgA (sIgA), and they report the results of measurements of serum sIgA concentrations in patients with chronic, nonalcoholic liver disease or carcinoma. Above-normal sIgA concentrations (greater than 25 micrograms/mL) were found in 22 of 38 sera from patients with chronic active liver disease and in 37 of 40 sera from patients with primary biliary cirrhosis. Markedly increased concentrations (greater than 118 micrograms/mL) were specific for primary biliary cirrhosis. Above-normal sIgA concentrations were found frequently in patients with colorectal (29/86, 34%), pancreatic (38/70, 54%), gastric (11/30, 37%), or mammary (6/46, 13%) carcinoma. An above-normal concentration of sIgA was more specific for hepatic metastases than an above-normal alkaline phosphatase activity in each type of carcinoma. The authors conclude that measurement of sIgA in serum is a useful diagnostic test in patients with chronic liver disease suspected of having primary biliary cirrhosis or in patients with carcinoma suspected of having hepatic metastases.

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