PRF1 and precursor B-cell acute lymphoblastic leukemia: In this study, we found that the co-expression of B7-H3 and LAG3 on activated CD4+ T cells strongly correlates with higher levels of cytotoxicity-related molecules such as GZMB, Perforin, and CD107a in both LCL-induced CD4 CTLs from human peripheral blood and CD4+ T cells derived from the bone marrow of B-ALL patients.