Plioplys et al. (1994) and Warren et al. (1992) demonstrated that a substantial number of subjects with autism have an increased number of HLA DR + activated T cells. Ashwood et al. (2004) found a higher number of B cells and NK cells in children with autism compared to controls as well as increased markers of cellular activation such as CD38 on B Cells, HLA-DR and CD26 on T cells subsets. Here, CD38 is linked to autism.