Reduction of tissue transglutaminase autoantibody levels by gluten-free diet is associated with changes in subsets of peripheral blood lymphocytes in children with newly diagnosed coeliac disease

Tissue transglutaminase (tTG) autoantibodies decline after gluten-free diet in patients with coeliac disease. We tested the hypothesis that gluten-free diet-induced change in tTG autoantibody levels affects subsets of peripheral blood lymphocytes. Peripheral blood was obtained from 20 children with biopsy-proven active coeliac disease. Gluten-free diet was initiated and the children examined again after three and six months. tTG autoantibodies were measured in radioligand binding assays and lymphocyte subsets by flow cytometry. IgA-tTG levels at diagnosis, 2204 U/ml (median, range 113–24990), were reduced over six months to 76 U/ml (median, range 1–1261) (P< 0·001). At six months, 12/20 (60%) children had reduced their IgA-tTG levels to < 100 U/ml and these children showed a decrease in B cells (mean change −3·8%, P = 0·014), CD4+ T cells (mean −4·32%, P = 0·011) and CD4+ T cells expressing CD25high (mean change −0·62%, P = 0·036). In contrast, the CD4+CD25highCCR4+ T cell population increased during the same period (mean change 11·5%, P = 0·0036). The decline in IgA-tTG levels correlated to the decrease in B cells (r= 0·56, P = 0·01), CD4+ T cells (r= 0·66, P = 0·004) as well as CD4+CD25high T cells (r= 0·59, P = 0·01). A negative correlation was found between the decline in IgA-tTG and CD4+CD25high T cells expressing CD45RO (r = –0·49, P = 0·03) and CCR4 (r = –0·54, P = 0·01). This is the first observational study on the effect of gluten-free diet on concurrent changes of tTG autoantibodies and specific peripheral blood lymphocyte subsets. Our data suggest that flow cytometry may be a useful complement to tTG autoantibodies when studying the effects of gluten-free diet in children with coeliac disease.