Activation of the alternative pathway by gluten. A possible aetiological factor in dermatitis herpetiformis.

Gluten fractions are shown to activate the alternative pathway of complement when added to normal human serum. Breakdown of C3 and Factor B occur in a manner analogous to that when activated by zymosan, in the presence of MgEGTA and in serum devoid of classical pathway activity. The suggestion is made that bypass activation may be the primary event when gluten enters the serum across a damaged gut mucosa. Immune complexes containing non-complement fixing IgA antigluten antibody are carried to the skin where it is proposed that complexed gluten activates C3 and initiates an inflammatory reaction.