T-regulatory Cells in Acute Leukemia and their Relation with Induction Outcome

Background: The leukemic microenvironment has become an area of interest for researchers in recent times. Nonmalignant T and B lymphocytes form a significant part of leukemic microenvironment and are postulated to have an effect on its progression and behavior. These lymphocytes are constantly interacting with blasts and are actively involved in innate and acquired immune responses against these blasts. We decided to look at the role of T-regulatory lymphocytes in tumor surveillance and treatment outcome. Aim and Objectives: The aims and objectives of the study are to evaluate the role of T-regulatory lymphocytes in acute leukemia cases and its correlation with treatment outcome. Materials and Methods: We evaluated consecutive 55 acute leukemia cases to investigate the prognostic effect of T-regulatory cells (T-regs) in acute leukemia. The study period was between January 2021 and December 2021. All patients whose complete records were available till the completion of induction were included in the study. The immunophenotype used to characterize and evaluate T-regs was CD4(+)CD25(+) T lymphocytes. For comparison, a total of 10 healthy controls were included in the study. Clinicohematological parameters including fever, lymphadenopathy, hepatosplenomegaly, extramedullary involvement, day 1 total leukocyte count, and blast percentage in peripheral blood and bone marrow were studied and documented to establish any possible correlation with T-regs percentage and treatment outcome. The treatment outcome evaluated in the study was complete remission postfirst induction. Results: As compared to those of healthy participants, the frequencies of CD4(+)CD25(+) T-regs in the peripheral blood of acute leukemia patients were significantly increased (1.5% [range: 0.50%-4.3%] vs. 0.58% [range: 0.40%-1.05%], P = 0.0001). Furthermore, the frequencies of CD4(+)CD25(+) T-regs in the peripheral blood of acute leukemia patients who did not achieve remission were significantly increased as compared to those who achieved remission (2.9% [range: 0.20%-4.3%] vs. 1.3% [range: 0.30%-2.9%], P = 0.002). No significant correlation was noted in the T-reg cells and parameters such as fever, lymphadenopathy, hepatosplenomegaly, extramedullary involvement, day 1 total leukocyte count, and blast percentage. Conclusion: This study suggests the possibility of using T-regs percentages as a prognostic indicator of acute leukemia and possible role of anti-T-regulatory immunomodulators in improving the outcome of disease.