Fig. 4.

a Celiac disease patient IgA (CD IgA) significantly increased the extracellular enzymatic activity of TG2 in endothelial cells when compared to control patient antibodies (non-CD IgA) whereas commercial transglutaminase 2 (TG2) antibody, CUB7402 had no effect. The co-administration of site-directed TG2 inhibitor, R281 prevented the enhancement of the TG2 activity. Bars represent mean TG2 activity in arbitrary units (AU). b Western blot analysis of TG2 expression in endothelial cells without any treatment (basal) and after administration of non-CD and CD IgA. Data are representative of three independent experiments. c Celiac disease (CD) patient IgA (n = 3) and CD patient serum samples (n = 20) bind to purified TG2 both in the presence and absence of R281 in enzyme-linked immunoassay