Figure 1.

Overview of the immune system as a mediator of behavior. Understanding how immune dysfunction in ASD can lead to changes in behavior requires understanding a complex network of interactions between several cell types from both the innate and adaptive arms of the immune system. Several immune factors mediate effects of CNS function. T-cell and NK-cell subpopulations may have altered activity and an impaired reaction to stimulation. Some cytokines can inhibit neurogenesis and promote neuron death, while others can promote the growth and proliferation of neurons and oligodendrocytes. Complement proteins and microglia can participate in synaptic scaling and pruning, while brain-reactive autoantibodies can change the development or function of neurons. When the many components of the immune system are dysregulated, these networks can lead to changes in neurodevelopment and behavior.