CD4 and autoimmune thrombocytopenic purpura: The results of flow cytometry showed that the percentage of CD8+ T cells was elevated but CD4+ T cell percentage was lowered in the ITP group in contrast to the Control group (Figure 3e–g, p < 0.001) and interestingly, ITP-induced increase of CD8+ T cells and decrease of CD4+ T cells in mouse peripheral blood was reversed in the absence of HLA-DRB5 (Figure 3e–g, p < 0.001).