title: Reduced levels of immunoglobulin in children with autism correlates with behavioral symptoms.
abstract: OBJECTIVE
  To assay if plasma antibody levels in children with autism or developmental delays (DD) differ from those with typical development as an indicator of immune function and to correlate antibody levels with severity of behavioral symptoms.
  
  
  METHODS
  Plasma was collected from children with autistic disorder (AU; n=116), DD but not autism (n=32), autism spectrum disorder but not full autism (n=27), and age-matched typically developing (TD) controls (n=96). Samples were assayed for systemic levels of immunoglobulin (IgG, IgM, IgA, and IgE) by enzyme-linked immunosorbent assay. Subjects with autism were evaluated using the Autism Diagnostic Observation Schedule and the Autism Diagnostic Interview-Revised, and all subjects were scored on the Aberrant Behavior Checklist (ABC) by the parents. Numerical scores for each of the ABC subscales as well as the total scores were then correlated with Ig levels.
  
  
  RESULTS
  Children with AU have a significantly reduced level of plasma IgG (5.39+/-0.29 mg/mL) compared to the TD (7.72+/-0.28 mg/mL; P<0.001) and DD children (8.23+/-0.49 mg/mL; P<0.001). Children with autism also had a reduced level of plasma IgM (0.670.06 mg/mL) compared to TD (0.79+/-0.05 mg/mL; P<0.05). Ig levels were negatively correlated with ABC scores for all children (IgG: r=-0.334, P<0.0001; IgM: r=-0.167, P=0.0285).
  
  
  CONCLUSIONS
  Children with AU have significantly reduced levels of plasma IgG and IgM compared to both DD and TD controls, suggesting an underlying defect in immune function. This reduction in specific Ig levels correlates with behavioral severity, where those patients with the highest scores in the behavioral battery have the most reduced levels of IgG and IgM.
authors.affiliation: Division of Rheumatology, Allergy and Clinical Immunology, University of California at Davis, Davis, California 95616, USA.
authors.forename: Luke
authors.initials: L
authors.lastname: Heuer
authors.forename: Paul
authors.initials: P
authors.lastname: Ashwood
authors.forename: Joseph
authors.initials: J
authors.lastname: Schauer
authors.forename: Paula
authors.initials: P
authors.lastname: Goines
authors.forename: Paula
authors.initials: P
authors.lastname: Krakowiak
authors.forename: Irva
authors.initials: I
authors.lastname: Hertz-Picciotto
authors.forename: Robin
authors.initials: R
authors.lastname: Hansen
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Croen
authors.forename: Isaac N
authors.initials: IN
authors.lastname: Pessah
authors.forename: Judy
authors.initials: J
authors.lastname: Van de Water