Αντισώματα έναντι της ιστικής διαγλουταμινάσης σε ασθενείς με ηπατικά νοσήματα

Abstract

The development of autoimmunity to tissue transglutaminase is a striking feature of coeliac disease, an enteropathy that develops in genetically susceptible individuals upon exposure to dietary gluten. IgA anti-t TG autoantibodies are present in at least 98% of coeliac patients and provide a very useful tool for the diagnosis of the disorder. In order to determine the presence of antibodies against tissue transglutaminase in patients with liver diseases and to determine the prevalence of CD in the same group of patients, serological screening was performed in the sera of 47 patients. Screening for IgA EMA t TG with indirect immunofluorescence (IIF) in monkey esophagus and human umbilical cord substrates has been performed. This assay is the optimum test for predicting CD but this indirect immunofluorescence test is not easy to apply in large scale screening. However, tissue transglutaminase has recently been identified as the main autoantigen recognized by EMA in CD patients. Several commercial ELISA tests based on different types of transglutaminases were developed in order to detect the presence of anti-t TG autoantibodies. Two different commercial ELISA'S (INOVA, HYCOR) were used in our study, in the detection of IgA anti-human t TG antibodies. The screening of the sera of hepatic group patients for IgA EMA antibodies with IIF in both substrates had been negative with the appearance of an EMAlike pattern. On the contrary, the screening for IgA anti-h-t TG antibodies with both the two ELISA'S showed possitivity in the majority of the samples. This combination of results EMA-/anti-h-t TG+ had been excluded the possibility of coexistence of coeliac disease with liver diseases in our samples. On the other hand, positive anti-h-t TG antibodies that were observed were thought to be false positive. Regarding the cause of these 'false positive' anti-t TG antibodies, we demonstrated that this phenomenon was probably linked to the presence of a variety of proteins in the samples such as transaminases, immunoglobulins, autoantibodies that were co-reacted with antibodies and gave that 'background' phenomenon that is been characterized by false positive anti-t TG antibodies.