Researchers injected mice with an acid that mimics a viral infection. This caused the pregnant mice's immune system to produce a chemical called IL-17a.
Mice exposed to higher IL-17a levels in the womb exhibited autism-like symptoms when they were born.
For example, they had trouble telling the difference between another live mouse and a toy.
They interacted with both equally, whereas normal mice spent more time socially interacting with live mice.
Yet, blocking the action of Th17 cells completely restored normal structure and function to the brains of the study offspring.
This was regardless of whether the changes were achieved by treatment with antibodies or by shutting down the IL-17a gene.
'To our knowledge, this is the first study to identify a specific population of immune cells that may have a direct role in causing behaviors linked to autism,' said immunologist study author Dan Littman at NYU Langone.