Background and Aim: PD-1 (programmed death-1) is an immune checkpoint receptor that modulates T-cell activity in peripheral tissues via interaction with its ligands, PD-L1 (programmed death-ligand 1) and PD-L2 (programmed death-ligand 2). Tumor cells upregulate PD-L1 or PD-L2 to dampen this T lymphocyte attack. Our goal was to demostrate the PD-1 and PD-L2 expresion rate of various hematologic malignancies, and to evaluate whether PD-1 and PD-L2 expresion have impact on prognosis.
Materials and Methods: For this purpose, pre-treatment bone marrow biopsy specimens of 83 patients [42 multiple myeloma (MM), 21 acute leukemias, and 20 chronic lymphocytic leukemia (CLL)] have been stained with monoclonal antibody immunstains of PD-1 and PD-L2.
Results: As a result, the overall expression rate of PD-1 was 26.2%, 4.8%, and 60% in patients with MM, acute leukemias, and CLL, respectively. Whereas, PD-L2 expression rate was 61.9%, 14.3%, and 10% in patients with MM, acute leukemias, and CLL, respectively.
Conclusion: Finally, we conclude that the role of PD-1 pathway can be demonstrated by immunohistochemistry (IHC). Since we have evaluated whether there is a correlation between (IHC) results and survival of patients with MM, acute leukemias, and CLL, we couldn’t demonstrate a meaningful evidence that these markers have an impact on prognosis.
Key Words: PD-1, PD-L2, multiple myeloma, acute leukemias, chronic lymphocytic leukemia.