Degree of Malignancy of T-Cell Acute Lymphocytic Leukemia Related to Autofluorescence in an EL4-Based Model

T cell acute lymphocytic leukemia (T-ALL) is an aggressive hematologic malignancy in terms of its pathology and populations. It is important to understand the phenomenon of autofluorescence in living cells because normal and cancer cells can be distinguished by this feature. However, the autofluorescence link to T-ALL is poorly understood. We provide direct evidence that EL4-based T-ALL model expresses both high autofluorescence (FL1+) and low autofluorescence (FL1-) in the current study. The FL1+ phenotype is not as stable as the FL1-phenotype. Interestingly, CD25+ cells of FL1+ can transform to CD25+ cells when injected into mice. Autofluorescence associated with differential expression of CD25 is related to the malignant degree of disease, which is presented by the tissue infiltration and growth speed of EL4 cells. Of note, the phenotypes of autofluorescence and CD25 expression of EL4 cells are related to the sensitivity to NK cells killing and the survival time of EL4-treated leukemic mice in vivo. Thus, autofluorescence monitoring might provide as new insight for investigating the malignant degree and prognosis index of T-ALL.