Reduced levels of immunoglobulin in children with autism correlates with behavioral symptoms.
Low antibody levels go hand-in-hand with tougher autism behaviors, so immune status may color what you see in session.
01Research in Context
What this study did
Heuer et al. (2008) drew blood from children with autism, kids with other delays, and neurotypical peers. They measured two antibody proteins: IgG and IgM. Then they compared the levels to each child’s behavior scores.
What they found
Children with autism had lower IgG and IgM than both other groups. Lower antibody numbers lined up with worse behavior ratings. The drop in immunity tracked with more severe symptoms.
How this fits with other research
Pritchard et al. (1987) tried the same idea with serotonin but found no clear link to behavior. Their old null result makes the new Ig finding stand out.
Muller et al. (2023) later showed that fever can briefly improve autism behavior when the immune system is stirred. Luke’s low-Ig data fits this immune-behavior story, but in the opposite direction: weak immunity, worse behavior.
Agiovlasitis et al. (2025) recently found two plasma proteins that also correlate with autism severity. Together these papers build a pattern: blood signals can mirror how tough the day looks for the child.
Why it matters
You can’t fix Ig levels with ABA, yet knowing a child runs low may explain frequent illness or fatigue that worsens learning. Share the lab slip with the pediatrician and schedule sessions when the child is healthy. Track sick days against behavior data—if problems spike before a cold, medical follow-up may prevent bigger setbacks.
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02At a glance
03Original abstract
OBJECTIVES: 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). CONCLUSION: 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.
Autism research : official journal of the International Society for Autism Research, 2008 · doi:10.1002/aur.42