Levels of pro-inflammatory cytokines (IL-6, TNF) in the serum of autistic children have been inconclusive. However, recent findings indicate that chemokines (eotaxin, MCP-1, RANTES) are elevated in this population. These chemokines are responsible for accumulation of mast cells and mast cell activation, and they have been shown to be associated with autism. In this research project, levels of IL-9, IL-33, and TSLP, new cytokines recently considered “alarmins” through mast cell activation, will be measured in the serum of autistic children along with age and sex-matched neurotypical controls. Interactions among these key molecules may prove useful for both potential biomarkers and novel targets for treatment.