A new study from the University of California Davis, published in the journal Pediatrics, points to the fact that children with autism have a deficient immune system. The study was conducted using blood samples of children enrolled in the Childhood Risk of Autism and the Environment (CHARGE) Study and included 10 children with severe autism age 2 to 5 and 10 age-, race- and sex-matched children who were developing typically.
The deficiency is in the form of granulocytes which exhibit one third capacity to fight infection and protect the body from cell invasion and deficiencies in the cells’ ability to fuel brain neurons might lead to some of the cognitive impairments associated with autism. Higher levels of free radicals also might contribute to autism severity
The cells are less capable of promoting the needed oxidative response to combat invading pathogens and the mitochondria in these cells consume far less oxygen. Mitochondria are the main intracellular source of oxygen free radicals, which are very reactive and can harm cellular structures and DNA. Cells can repair typical levels of oxidative damage. However, in the children with autism the cells produced more free radicals and were less able to repair the damage, and as a result experienced more oxidative stress. The free radical levels in the blood cells of children with autism were 1 ½ times greater than those without the disorder.
“Granulocytes fight cellular invaders like bacteria and viruses by producing highly reactive oxidants, toxic chemicals that kill microorganisms. Our findings show that in children with severe autism the level of that response was both lower and slower,” said Eleonora Napoli, lead study author and project scientist in the Department of Molecular Biosciences in the UC Davis School of Veterinary Medicine. “The granulocytes generated less highly reactive oxidants and took longer to produce them.”
“The response found among granulocytes mirrors earlier results obtained with lymphocytes from children with severe autism, underscoring the cross-talk between energy metabolism and response to oxidative damage,” said Cecilia Giulivi, professor in the Department of Molecular Biosciences in the UC Davis School of Veterinary Medicine and the study’s senior author.
“It also suggests that the immune response seems to be modulated by a nuclear factor named NRF2,” that controls antioxidant response to environmental factors and may hold clues to the gene-environment interaction in autism, Giulivi said.
E. Napoli, S. Wong, I. Hertz-Picciotto, C. Giulivi. Deficits in Bioenergetics and Impaired Immune Response in Granulocytes From Children With Autism. PEDIATRICS, 2014; 133 (5): e1405 DOI: 10.1542/peds.2013-1545