Immune system dysfunctions may represent one of the causes or phenotypes of autism spectrum disorders. Recently, investigators at the Children’s Center for Environmental Health (CCEH) at UC Davis demonstrated that some families affected by autism show disruptions in immune system signaling. This includes the presence of an abnormal antibody in the blood of a subset of mothers with an affected child, as well as disrupted immunological profiles of immune markers in some children who are affected. The CCEH has been investigating the mechanism by which environmental factors interact with the immune system to result in developmental disorders, including ASD. In order to complete key experiments focused on the flame retardants PBDEs (Polybrominated diphenyl ethers) and how they interact with the immune system to produce deleterious effects during development, two lines of investigation are key: the outcomes of animals exposed to PBDE during gestation, focusing on behavioral endpoints relevant to autism and immunohistochemical findings; and the immune response in blood samples taken from children affected by autism and those not affected by autism in response to PBDEs. Better understanding of the mechanisms involved in disruption of the immune system in ASD, especially environmental factors which exacerbate or trigger an immune response, will not only identify modifiable risk factors, but better define the cellular mechanism by which this occurs for more targeted biomarkers.