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15 Dynamic of Anti-Transglutaminase Autoantibodies in the Follow-Up of Celiac Children with Gluten Free Diet: Comparison of IgG and IgA

Introduction: During the last few years, autoantibodies against tissue transglutaminase (tTGase) have proven to be the most sensitive and specific humoral markers for celiac disease. Traditionally, IgA subclass immunoglobulins are determined in celiac patients, but IgG antibodies also exist, and at least at the time of diagnosis, perform equally well as IgA, with the additional advantage that IgG are also present in IgA-deficient individuals. Nevertheless, little is known on the outcome in terms of frequency and titres, of both antibodies once gluten is removed from diet.Aim: To investigate the evolution of IgA and IgG autoantibodies against tTGase in celiac patients on gluten-free diet (GFD)Methods: Serum samples from 69 celiac children were taken at diagnosis and after 15 days, 1, 2, 4, 6, 12, 18 and 24 months on GFD. The presence of tTGAse autoantibodies was determined with a radioassay using in vitro transcribed-translated human recombinant tTGAse, and immune complexes were precipitated with protein A- or anti-IgA-agarose for IgG and IgA, respectively. Antibody levels were calculated using an 8-point serial two-fold dilution of a positive sample, and are expressed as a standard deviation score (SDS), relative to the mean and SD of 100 non-celiac controls. According to the presence of HLA-DR3, patients were subdivided into homozygous, heterozygous or non-DR3.Results: The evolution of the prevalence of IgA and IgG class autoantibodies against tTGase is shown on the table. No differences were observed when patients were stratified according to their HLA status. Figure 1Conclusions: Overall, there are no differences in the performance of IgG and IgA class autoantibodies in the evolution of celiac patients. Antibody positivity is above 30% during the first year after removal of gluten, but decreases to less than 5% during the second year. HLA-DR3 does not seem to influence the frequency of neither IgA nor IgG tTGase autoantibodies.