A new study has found that prenatal exposure to maternal antibodies can lead to autistic behaviours in kids.
The study, by researchers at UC Davis M.I.N.D. Institute and Center for Children's Environmental Health, found that antibodies in the blood of mothers of children with autism bind to foetal brain cells, potentially interrupting healthy brain development.
The researchers also noted that the reaction was most common in mothers of children with the regressive form of autism, which occurs when a period of typical development is followed by loss of social and/or language skills.
The findings are important as they raise the possibility that the transfer of maternal antibodies during pregnancy is a risk factor for autism.
"This is one of the first studies to identify immunological factors in mothers that could be linked to autism in the very earliest stages of life," said Judy Van de Water, senior author of the study and professor of rheumatology, allergy and clinical immunology.
"Our results should lead to more research on the prenatal environment and the onset of autism. We are also optimistic that in the future a prenatal test and therapeutic intervention preventing IgG exposure during pregnancy could protect some children from ever getting autism."
Van de Water and her team began their research with blood samples from 123 mothers - 61 whose children have autism and 62 whose children are typically developing.
They isolated IgG antibodies from the samples then exposed the antibody to foetal brain tissue by western blot analysis, which detects antibody reactivity to proteins. The outcome revealed a highly specific reactivity pattern to two foetal brain proteins in seven of the 61 samples from the autism group, six of which were from mothers of children who had regressive autism. None of the IgG samples from mothers in the control group produced this same result.
"We're not entirely sure why the IgG response against fetal brain proteins was so specific for later onset autism," said Van de Water.
"It's possible that early exposure to maternal antibodies sets in motion a biological path to autism with the behavioral outcomes not apparent until much later. It's also possible that an environmental exposure sometime after birth could be required to set this process in motion. We are hopeful that this study will help build our understanding of the foundations of the regressive form of the disorder."
IgG antibodies are responsible for long-term immune system responses to infection, but they can also contribute to autoimmune diseases such as arthritis, multiple sclerosis and lupus.
IgG also crosses the placenta in order to provide key immune system protectants to a growing fetus and newborn child, which is a key reason why Van de Water decided to investigate the role of IgG as a potential factor in autism.
"This finding is important because it provides important clues about the potential maternal contributions to autism risk in a subset of children who may develop autism," said Isaac Pessah, director of the UC Davis Center for Children's Environmental Health and professor of molecular biosciences.
The study is to be published in the March 2008 issue of Neurotoxicology.