More definitive studies have since highlighted thepresence of inflammation in the brain and the activation of microglia [11] as well asevidence for altered peripheral immune function in autism, including increasedcytokine levels in the plasma such as interleukin (IL)-1β, IL-6, and IL-8 [12], elevatedlevels of complement proteins [13], decreased cellular activity of NK cells [14]–[16], increasedmonocyte activation [17], [18], and a reduced number of CD4+ T cells [10], [19], [20]. Here, CD4 is linked to autism.