Serum antibodies to carbonic anhydrase I and II in patients with idiopathic chronic pancreatitis and Sjogren's syndrome

Background and Aims: Patients with idiopathic chronic pancreatitis and Sjogren's syndrome show immune responses against a 60-kilodalton protein isolated from human pancreas extracts. Monoclonal antibody SP3-1, raised against the 60-kilodalton protein, reacts with ductal cells in several exocrine organs and cross-reacts with human carbonic anhydrase II. The present study evaluated serum from patients with these diseases for antibodies to human carbonic anhydrase I and II. Methods: An enzyme-linked immunosorbent assay was used to quantify serum antibody against carbonic anhydrase I and II. Results: Serum antibodies against carbonic anhydrase I and II were detected in 7 and 11 of 33 patients with idiopathic chronic pancreatitis, respectively, and in 8 and 13 of 21 patients with Sjogren's syndrome, respectively. The positive prevalence rates of patients with antibodies to carbonic anhydrase II were significantly different among patients with idiopathic chronic pancreatitis and Sjogren's syndrome compared with normal patients (1 of 21). There were no significant differences in the prevalence rates of patients with alcoholic chronic pancreatitis (3 of 20), gallstone-related chronic pancreatitis (0 of 7), and primary biliary cirrhosis (1 of 11). Conclusions: The results suggest that carbonic anhydrase II is one candidate target antigen recognized during the autoimmune pathophysiology observed in idiopathic chronic pancreatitis and Sjogren's syndrome.