The expression of CD11b, a marker of microglial activation, was upregulated in cerebral cortical microglias incubated with sera from children with OMS and NB (3.41 ± 0.32 ng/mg total protein OMS + NB, 0.99 ± 0.09 ng/mg total protein NB, 1.09 ± 0.12 ng/mg total protein healthy control, p < 0.001 vs NB, p < 0.001 vs healthy control), whereas CD11b concentration was not statistically changed by sera of children with only NB at least under our experimental conditions (Fig. 1a). This evidence concerns the gene ITGAM and opsoclonus-myoclonus syndrome.