Paediatric coeliac disease and dermatitis herpetiformis: differences in complement activation in relation to diet.

We studied complement (C') involvement in paediatric coeliac disease (CD) and dermatitis herpetiformis (DH) in relation to lesions and function of enteric mucosa and to diet. For this purpose, 50 children affected by CD and 42 affected by DH were subdivided in 3 groups: in the first (I) were included subjects in free diet, in the second (II) children during gluten-free diet (GFD) and in the third (III) subjects after gluten reintroduction in diet. Only in CD we found significant modifications of some C' parameters. In fact C3 and C4 levels increase in II group in GFD (respectively p less than 0.02 and p less than 0.03) and result inversely correlated to an arbitrary score for the evaluation of the enteric histological lesions (p less than 0.02 and p less than 0.01). C3d/C3 ratio levels, as catabolic index of C3, result always greater than normal in both diseases, but significantly decrease only in II group of CD children (p less than 0.02), where they result also positively correlated to the histological score (p less than 0.05). Circulating immune complex-like material is higher in DH, but incidence of pathological values decrease in II group only in CD (p less than 0.04). These data suggest probable significant differences in the pathogenetic mechanisms of CD and DH involving C'.