Purpose: Assessing the possibility of finding tumor-infiltrating lymphocytes (TIL) in bone marrow of acute myeloid leukemia (AML) patients and evaluating the anti-tumor activity of these TIL against autologous AML cells.
Patients and methods: TIL were immunomagnetically isolated by using anti-CD3 from bone marrow samples of 20 patients at the presentation of AML or four weeks upon completion of chemotherapy. TIL were ex vivo expanded for two weeks and immunophenotyped. Functionality in terms of cytokine secretion and cytotoxicity was assessed by γ-interferon quantitation and Elispot assay, respectively.
Results: TIL were detected in bone marrow samples of 50% (10/20) of the patient cohort. They were noted to highly express CD137 and PD-1 and display a significantly higher anti-tumor reactivity compared to that of autologous peripheral blood lymphocytes. TIL could be expanded in co-cultures with irradiated feeder cells supplemented with interleukin (IL)-7 and IL-15.
Conclusion: Data suggested the presence of reactive γ-interferon-secreting TIL in AML patients. They are expandable and possess anti-tumor activity, which might have a great potential in the development of adoptive cellular therapy for AML.
Keywords: tumor-infiltrating lymphocytes, acute myeloid leukemia, adoptive cell therapy, immunotherapy