Maternal antibodies may cause autism

By: Sam Ohmer

Posted: 3/6/08

An infant's health is at the forefront of every pregnant woman's mind. There are many factors that can be controlled - taking the right vitamins, eating the correct foods. But research on autism, a devastating disorder of brain development, indicates that sometimes a mother's body can affect a child's health unintentionally.

A group of researchers at Hopkins has found evidence that a mother's immune system might trigger the eventual development of autism in her child.

"Despite an intense research focus, the underlying etiology for most children affected with autism is unknown," said Harvey Singer, a pediatric neurologist at Hopkins and the lead author on the study.

Autism appears in the first few years of childhood, usually at four or five years of age. Some signs are visible even earlier; at birth, babies with autism have smaller brains compared to non-affected infants. About one in 150 children are diagnosed with the disorder.

Characteristic symptoms include problems with social interaction, including communication and language, as well as repetitive behaviors.

Research has shown that environmental, genetic and immunological factors can all play a role in the development of autism.

Singer and colleagues at Hopkins and the Hopkins-affiliated Kennedy Krieger Institute, which specializes in childhood development, undertook a study to look at the role of the immune system in the onset of autism.

"This study represents only the initial step in proving an immunological association with autism," Singer said.

Antibodies are part of the body's immune system. They are sent out to mark foreign particles in the body for destruction. Unfortunately, antibodies can sometimes turn against the body it is supposed to protect, recognizing the wrong substances and setting off an inappropriate attack on healthy cells.

It is known that certain antibodies can be passed from mother to child; this mechanism accounts for the passive immunity babies are generally born with.

Singer and his group found that, in some cases of autism, pregnant women's bodies actually raise antibodies against their babies, which sets off a series of events that slowed the normal development of the infants' brains.

The team found that mothers of children with autism had heightened levels of certain antibodies during their pregnancies. "The presence of specific antibodies correlated with the presence of developmental regression in the affected child," Singer said.

"About 40 percent of mothers with autistic offspring had significant differences on Western immunoblots," Singer said, referring to analyses conducted on fetal fluids to measure levels of certain anti-brain antibodies.

This finding suggests that there may be a truly devastating link between maternal antibodies and autism. Singer's team and others are now moving toward a greater understanding of the causes of the illness.

The next step of the research is aimed at trying to discover which proteins are engaged in this immunological backfiring, in hopes of being able to prevent this process.