GZMB and neoplasm: Plasmodium infection simultaneously upregulates the expression levels of co-stimulatory (such as CD40L, OX-40, GITR) and co-inhibitory checkpoint molecules (such as PD-1, CTLA-4, TIM-3) on CD8+ T cells in tumor-bearing mice, but these CD8+ T cells express high levels of effector molecules (such as perforin and granzyme B) at the same time, representing the increase of their cytotoxicity.