Wheat and milk proteins, including gluten and casein, have been suspected of having a role in autism spectrum disorders (ASD). However, while the rate of the use of gluten and/or casein exclusion diets in children with autism is increasing, the evidence for efficacy of these diets remains weak. At the same time, there is lack of consensus with regard to reports of elevated immune response to gluten and casein or increased concentrations of specific gluten and casein peptides in ASD. The aims of this project represent a systematic exploratory approach to examine the relevance of gluten and casein to ASD in a controlled study. ASD patients, celiac disease patients, and healthy individuals will be tested for levels of antibodies to gluten, casein, deamidated gluten, and the transglutaminase enzyme. The specificity of the immune response to the various gluten (gliadin and glutenin) and casein (alpha, beta, and kappa) molecules will be assessed by chromatography, mass spectrometry, and immunologic assays. Patient and control serum specimens will be assessed for the presence of specific gluten and casein peptides known to have opioid-like biological activity. The proposed experiments are expected to provide insight into the relevance of two commonly consumed groups of dietary proteins and the immune response against them in ASD. In addition, our proposed study to fully characterize the immune response to gluten and casein provides an opportunity to discover novel biomarkers that may become useful in identifying specific disease subtypes.