Autistic children exhibit undetectable hemagglutination-inhibition antibody titers despite previous rubella vaccination.

The etiology of autism is unknown, but autism has been associated with a number of diseases, including prenatal rubella. Rubella vaccine challenge was used in an attempt to retrospectively diagnose prenatal rubella in autistic children. This test was selected because unresponsiveness of antibody titer has been reported as helpful in retrospective diagnosing of prenatal rubella. Fifteen autistic children and 8 controls matched for age were challenged with rubella vaccine. Rubella vaccine challenge did not differentiate autistic children from the control subjects. However, 5 of 13 autistic children had undetectable titers despite previous vaccine; all control subjects had detectable titers. This finding of undetectable titers in autistic children suggests these children may have an altered immune response.