PRF1 and myelodysplastic syndrome: Our team analyzed in bone marrow samples from MDS patients by multicolor flow cytometry and found that compared to healthy controls, the proportion of the TIM3+ subpopulation of CD8+ T cells was significantly elevated in MDS patients, but the secretion of granzymes and perforin by this population of cells was decreased, along with the up-regulation of expression of apoptosis-sensitive marker CD95 (Fas), which suggests that there is functional exhaustion of TIM-3+ CD8+ T cells (28).