Low-avidity antibodies to carbonic anhydrase-I and -II in autoimmune chronic pancreatitis.

Antibodies (Abs) to carbonic anhydrase (isoforms CA-I and CA-II) have been considered pathogenic factors in the development of autoimmune pancreatitis. Besides, such autoAbs might accelerate the pancreatic damage in alcoholic chronic pancreatitis (CP). The aim of the present study was to evaluate the presence of serum Abs to CA-I and CA-II in CP and the relative affinity of these Abs. Serum anti-CA-I and -CA-II Abs were measured in 89 patients with CP (48 alcoholic and 41 nonalcoholic) by an ELISA technique. The prevalence of those autoAbs in CP was compared with other autoimmune diseases where they have also been found. The presence of other serological manifestations of autoimmunity, such as hypergammaglobulinemia or antinuclear Abs, was determined in CP patients as well. Elevated serum levels of both anti-CA-I (24%) and -CA-II (18%) Abs were observed in CP, although their prevalence was lower than in autoimmune diseases like rheumatoid arthritis (44 and 25%, respectively) or systemic lupus erythematosus (39% for anti-CA-I Abs). Furthermore, these Abs were of low average avidity. On the other hand, a significantly higher proportion of nonalcoholic CP had anti-CA-II Abs with respect to alcoholic CP (15.2 vs. 2.4%, p < 0.05). Anti-CA-I and -CA-II Abs might be helpful in the diagnosis of autoimmune CP, and the detection of the latter Abs seems to discard alcoholic etiology. Although it does not discard any pathogenic role in autoimmune CP, the low-avidity of anti-CA Abs argues against such idea.