Furthermore, CTLA-4 upregulation in different intratumoral T-cell populations, such as CD4+CD25highFoxp3+ Tregs, CD4+, and CD8+ T cells, has been associated with abnormal cytokine signaling and poor prognosis in B-ALL and aggressive pediatric sarcoma patients [53,54]. Here, CD4 is linked to precursor B-cell acute lymphoblastic leukemia.