HLA-C and leukemia: γδ T cells play an important role in the successful clinical outcome of αβhaplo-HSCT in pediatric patients with high-risk leukemias because they can recognize tumor cells without the need for major histocompatibility complex (MHC) presentation (47) and have potent anti-leukemia activity in the absence of relevant GvHD-inducing effect (35, 36, 48).