Autoantibodies against brain and bacterial polysaccharides are not well characterized in Autism Spectrum Disorders (ASD). Anti-streptococcal autoantibodies are well characterized in Rheumatic Fever and Sydenham chorea (SC) by human monoclonal antibodies (mAbs) and Immunoglobulin G (IgG) derived from SC. SC is a prototype movement and neuropsychiatric disorder recognized for autoimmunity developing from a bacterial infection. Other bacterial polysaccharides may play an important role in crossreactivity with brain such as in Streptococcus pneumoniae and Haemophilus influenzae type b. These studies are expected to determine potential antibody risk factors and potentially diagnostic tools to subset Autistic children for better diagnosis scales and more effective treatment if immune dysregulation is the underlying cause of some of their symptoms.