Two new studies add to the evidence that some children with autism have an altered immune response (Image: iStockphoto)
Children with autism show different immune system responses compared with other children, say US researchers.
Two studies presented to a conference on autism this week help to support other research that suggests subtle differences in the immune function of children with autism.
Autism is a brain disorder usually seen as children become toddlers. It has a spectrum of symptoms that include difficulty with social interaction and repetitive behaviours.
No one knows what causes autism, although experts have largely rejected links with childhood vaccines.
Scientists at the 4th International Meeting for Autism Research in Boston presented studies looking at the blood of children with autism.
Dr Judy Van de Water of the University of California, Davis, and colleagues separated immune cells from 30 children with autism and 26 ns. They mixed in toxins and bacteria.
In response to bacteria, the researchers saw lower levels of immune signalling proteins called cytokines in the group with autism. These children also had irregular responses to a plant protein, but not to other toxins or to a measles, mumps and rubella vaccine.
"Understanding the biology of autism is crucial to developing better ways to diagnose and treat it," Van de Water says.
A second team at the same centre took blood samples from 70 children aged four to six with autism and from 35 other children.
The children with autism had 20% more immune system cells called B cells and 40% more natural killer cells.
There also seemed to be differences in other proteins in the blood, although the researchers are still sifting through the data.
"From these results we think it is highly likely that there are differences we can detect in blood samples that will be predictive of the disorder, though we are still some years away from having an actual diagnostic blood test for autism," says researcher Professor David Amaral, who led the study.
"There is a growing view among experts that not all children with autism are 'doomed to autism' at birth," Amaral says.
"It may be that some children have a vulnerability, such as a genetic abnormality, and that something they encounter after being born, perhaps in their environment, triggers the disorder," he adds.
"Studying the biological signs of autism could lead to new ways to prevent the disorder from ever occurring. And even if it can't be prevented, intervening early in life, ideally shortly after birth, could greatly improve the lifetime outlook for children with autism."