The purpose of testing for anti-gliadin antibodies includes, in addition to diagnosis of gluten sensitive enteropathy, monitoring for compliance to a gluten free diet. IgA gliadin antibodies increase rapidly in response to gluten in the diet, and decrease rapidly when gluten is absent from the diet. The IgA anti-gliadin antibodies can totally disappear in 2-6 months on a gluten-free diet, so they are useful as a diet control. By contrast, IgG anti-gliadin antibodies need a long time, sometimes more than a year, to become negative.
The reverse is also true. That is, a patient with celiac disease who has been on a gluten-free diet and tests negative for IgA anti-gliadin antibodies, will show a rapid increase in antibody production when challenged by gluten in the diet. Approximately 90% of challenged patients will yield a positive IgA anti-gliadin result within 14-35 days after being challenged. The test results you reported are consistent with a patient who is conforming to a gluten-free diet.