Catalytic autoantibodies against myelin basic protein (MBP) isolated from serum of autistic children impair in vitro models of synaptic plasticity in rat hippocampus

•Autistic spectrum disorder (ASD) autoantibodies against myelin basic protein (MBP)•ASD autoantibodies to MBP of both the IgG and IgA classes, but not of the IgM class•ASD IgA autoantibodies behave as a serine proteinase and degrade MBP in vitro.•IgA autoantibodies cause a decrease of long-term potentiation in rat hippocampi.

Autoantibodies from autistic spectrum disorder (ASD) patients react with multiple proteins expressed in the brain. One such autoantibody targets myelin basic protein (MBP). ASD patients have autoantibodies to MBP of both the IgG and IgA classes in high titers, but no autoantibodies of the IgM class. IgA autoantibodies act as serine proteinases and degrade MBP in vitro. They also induce a decrease in long-term potentiation in the hippocampi of rats either perfused with or previously inoculated with this IgA. Because this class of autoantibody causes myelin sheath destruction in multiple sclerosis (MS), we hypothesized a similar pathological role for them in ASD.