We propose a double blind placebo-controlled crossover trial of TSO, where subjects would be randomized to receive placebo or TSO for 12 weeks, with a 4 week washout and then 12 weeks of the the treatment not yet received. To assess the effect on social cognition, repetitive behaviors, aggression and irritability, and global functioning in adults with autism spectrum disorder. The objectives of the proposed study are to develop an innovative treatment approach to autism by 1) assessing the safety and efficacy of TSO treatment using behavioral and laboratory outcome measures; 2) determining whether this treatment has sufficient promise to warrant consideration of a larger, multi-centered, placebo-controlled clinical trial; 3) conducting secondary analyses to explore the relationship between clinical features, immune mechanisms, and treatment response.