RESUMO
OBJECTIVES: Pancreatic ductal epithelia contain an abundance of carbonic anhydrase (CA), and the presence of antibodies to this enzyme has been described in autoimmune disorders. We previously found a small amount of an immunoglobulin G-like material in purchased CAII reagents, which led to pseudopositive reactions. METHODS: We determined the optimum measurement conditions for detecting anti-CAII antibody using an enzyme-linked immunosorbent assay and sera from 140 patients with pancreatic diseases. RESULTS: Compared with the prevalence of anti-CAII antibody in healthy subjects, a significantly higher seroprevalence of the antibody was detected in patients with autoimmune pancreatitis (AIP) (88.9%, P < 0.02), Sjögren syndrome (67.6%, P < 0.01), and alcoholic chronic pancreatitis (45.8%, P < 0.01). No positive results were obtained among patients with pancreatic cancer. Moreover, the antibody value obtained in the pancreatic cancer patients was actually lower than that obtained in healthy subjects. CONCLUSIONS: The anti-CAII antibody is probably not a specific marker of AIP because it was present at a higher frequency in the sera of patients with other pancreatic diseases. Nevertheless, the anti-CAII antibody may be a useful tool for the differential diagnosis of AIP and pancreatic cancer.
Assuntos
Autoanticorpos/sangue , Doenças Autoimunes/diagnóstico , Anidrase Carbônica II/imunologia , Neoplasias Pancreáticas/imunologia , Pancreatite Alcoólica/diagnóstico , Pancreatite/diagnóstico , Síndrome de Sjogren/diagnóstico , Síndrome de Sjogren/enzimologia , Adulto , Idoso , Doenças Autoimunes/enzimologia , Doenças Autoimunes/imunologia , Diagnóstico Diferencial , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imunoglobulina G/sangue , Japão , Masculino , Pessoa de Meia-Idade , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/enzimologia , Pancreatite/enzimologia , Pancreatite/imunologia , Pancreatite Alcoólica/enzimologia , Pancreatite Alcoólica/imunologia , Síndrome de Sjogren/imunologiaAssuntos
Autoanticorpos/sangue , Doenças Autoimunes/diagnóstico , Anidrases Carbônicas/imunologia , Hepatite Autoimune/diagnóstico , Pancreatite/diagnóstico , Biomarcadores/sangue , Ensaio de Imunoadsorção Enzimática/métodos , Humanos , Immunoblotting/métodos , Cirrose Hepática Biliar/diagnóstico , Valores de Referência , Síndrome de Sjogren/diagnóstico , Manejo de EspécimesRESUMO
BACKGROUND: Immunoglobulin G autoantibody against carbonic anhydrase (CA) II has been detected in the sera of patients with a variety of autoimmune diseases. Antibody against CAII has also been described as a serological marker for distinguishing between cases of autoimmune cholangitis (AIC) and those of primary biliary cirrhosis (PBC). However, the optimal antibody measurement conditions (enzyme-linked immunosorbent assay: ELISA) have not yet been established. Moreover, we also found that a small amount of an IgG-like material exists in purchased CAII reagents, which causes pseudopositive reactions. METHODS: The sera of 96 patients with liver disease were examined for the presence of anti-CAII antibody using antigen (CAII) not containing the IgG-like material as the most suitable measurement conditions. Compared with the anti-CAII antibody prevalence of 3.8% found in normal subjects, a significantly higher seroprevalence of the antibody was detected in patients with PBC (31.0%, P<0.02), autoimmune hepatitis (AIH) (50.0%, P<0.01) and chronic viral hepatitis (27.5%, P<0.01). But, in cases of PBC, no significant correlation was noted between the level of anti-CAII antibody and the presence of anti-mitochondrial antibodies (AMA). CONCLUSIONS: While CAII may be a target antigen in autoimmune diseases, the anti-CAII antibody is not likely to be a specific marker of AIC. The optimum measurement conditions for the ELISA for anti-CAII antibody would provide us with valuable information to elucidate the underlying immunological abnormalities in liver diseases.