Nori Takei, M.D., Ph.D., of Hamamatsu University School of Medicine, Japan, is studying the possible role of immune system dysfunction in autism. Dr. Takei notes recent research indicating that microglia, the immune cells of central nervous system, have been found to be activated in autism postmortem brains. Using positron emission tomography (PET), his team observed increased microglial activation in the living brains of people with autism. Generally, microglia are activated in response to any pathological changes in the brain. Dr. Takei's team correlated microglial activation in a portion of the brain with the presence and activity of different neurotransmission systems. Activated microglia secrete either neuroprotective or neurotoxic factors, depending on the context. He hypothesizes that elevated microglial activation observed in the prior PET study has a neurotoxic effect, which leads to disturbances in serotonergic- and other neurotransmission systems. Takei's team will attempt to verify this hypothesis in diverse ways: via neuroimaging; blood studies (in a birth cohort and in adults); animal models; and gene-association studies. If successful, the work could lead to development of biomarkers for autism and new treatment strategies.