Maternal antibodies may contribute to autism
NEW YORK (Reuters Health) - Along with genetic, metabolic and environmental factors, a team of researchers at Johns Hopkins University in Baltimore suggest that autism may also be caused or triggered by maternal antibodies that cross over through the placenta and are directed against the brain tissues of the fetus, adversely affecting brain development.
Dr. Harvey S. Singer and colleagues note that children with autism have antibodies in the blood that react against brain tissue. Antibodies are an important part of the immune system in which proteins are produced and mount a defense in response to the presence of a foreign body, such as an invading virus.
Most studies into the origin of autism have focused on autoantibodies as a possible explanation. Autoantibodies are antibodies the body makes that react against the body's own tissues by mistake; this mechanism is involved in allergic reactions and autoimmune diseases.
However, another possible explanation involves the transfer of reactive antibodies from the mother through the placenta to the fetus.
To investigate the latter, the team measured the antibody-brain reaction in blood samples from 100 mothers with and 100 mothers without a child diagnosed with autism.
Mothers of children with autism had a stronger reactivity or more areas of reactivity between antibodies and brain proteins compared with mothers without an autistic child. The presence of maternal antibodies also correlated with having a child with developmental regression, a primary feature of autism.
"Our research suggests that the mother's immune system may be yet another factor or trigger in those already predisposed" to autism, Singer commented in a university release.
"The mere fact that a pregnant woman has antibodies against the fetal brain doesn't mean she will have an autistic child," Singer cautioned. "Autism is a complex condition and one that is likely caused by the interplay of immune, genetic and environmental factors."
The researchers are now studying the effect of maternal antibodies in pregnant mice. Preliminary results show that the offspring of mice injected with neural antibodies exhibit developmental and social behaviors suggestive of autism.
SOURCE: Journal of Neuroimmunology, February 2008.