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

Summary 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 CD25 high (mean change −0·62%, P  = 0·036). In contrast, the CD4 + CD25 high CCR4 + 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 + CD25 high T cells ( r  = 0·59, P  = 0·01). A negative correlation was found between the decline in IgA‐tTG and CD4 + CD25 high 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.