Study of Bone Marrow Lymphocyte Subset in Acute Myeloid Leukemia

Introduction  Acute myeloid leukemia (AML) is a heterogenous disorder consisting of clonal expansion of myeloblasts. Tumor immunity plays an important part in the pathobiology of AML. Understanding the components of tumor immunity is important for understanding tumor pathogenesis and the principles of immunotherapy. Methods  We studied 41 patients with AML, for total lymphocyte, CD4 positive helper T cells, CD8 positive cytotoxic T cells, and CD16/56 positive natural killer (NK) cells proportion. Quantification was done on bone marrow aspirate sample by flowcytometry. Whenever available, post induction bone marrow was also analyzed for the lymphocyte subset. Results  No significant difference was noted in the percentage of blasts among the three risk categories: favorable, intermediate, and adverse. However, there was significant difference in the total lymphocyte among the risk stratification groups, being highest in the favorable group and lowest in the adverse group. CD8 positive cytotoxic T cells were significantly less in Acute Promyelocytic Leukemia (APML) cases ( p  = 0.001). Total lymphocytes were, however, more numerous in APML ( p  = 0.005). NK cell proportion was not significantly different between APML and non-APML patients. On completion of induction chemotherapy, bone marrow samples for 12 patients could be processed for lymphocyte subset. On comparing the baseline against the post induction bone marrow, it was observed that there was significant increment in the proportion of CD4 positive T lymphocytes ( p  = 0.046). Conclusion  There is a difference in lymphocyte subset amongst patients with AML. Larger studies including functional aspects are needed to better define the role of lymphocytes in disease pathogenesis.