Immune Dysfunction in Autism Spectrum Disorders

A great number of studies have been done examining immune function in children with autism spectrum disorders (ASD). Most of these studies have demonstrated immune dysfunction, especially involving cellular immunity. Important to the immunoexcitotoxicity hypothesis is the finding that macrophages and lymphocytes from ASD children have been shown to demonstrate an amplified release of pro-inflammatory cytokines with stimulation, especially in those having gastrointestinal (GI) symptoms. Because of the intimate connection between the gut and brain, hyperimmune responses from the gut, vial vagal afferents, can rapidly activate brain microglia, leading to an exaggerated innate immune response within the brain. It has also been shown that ASD children often react to food peptides, such as gliadin, gluten and casein as well as a number of bacterial and fungal antigens, all of which can exaggerate immunoexcitotoxicity. The finding of cross-reacting food antigen with brain components also indicates the presence of bystander damage and would trigger immunoexcitotoxicity as well.