Specific circulating anti-gliadin IgG-class antibody does not mediate intestinal enteropathy in gliadin-fed mice

The effects of specific circulating IgG antibody on the uptake of dietary antigen and in the generation of intestinal enteropathy have been investigated in Balb/c mice bred on a gluten-free diet. A monoclonal IgG1 antibody (GD3) was prepared against gliadin. After adoptive transfer into mice, this antibody was capable of mediating a type III hypersensitivity response in vivo to footpad challenge with gliadin. The titres of circulating GD3, as estimated in vitro by ELISA, correlated well with the degree of inflammation at sites of type III responses in vivo. Following footpad challenge with gliadin, titres of circulating GD3 antibody were reduced. GD3 antibody was tested for its ability to mediate inflammatory responses in vivo in the intestinal mucosa of mice fed with gliadin. Circulating GD3 antibody was removed selectively and specifically by dietary gliadin, compared to feeding with bovine serum albumin or maintenance on a gliadin-free diet only. However, we were unable to demonstrate any pathological changes in the intestine as a result of possible local antigen-antibody complex formation or deposition. Using radio-iodinated gliadin as a trace marker, no significant retention of gliadin in the intestinal mucosa was found in mice pre-injected with GD3 antibody. These data suggest that circulating IgG antibody has little effect on dietary antigen uptake in the gut, and alone is insufficient to mediate an enteropathy.