Özet:

Objective: 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 T lymphocyte attack. The checkpoint inhibition by tumor cells via the PD-1 pathway suppress the antitumor immune response. The role of PD-1 pathway has been extensively investigated in non-hematologic malignancies, however, the exact role of this pathway is not established in hematologic disorders. So, we aimed to demostrate the PD-1 and PD-L2 expresion rate of various lymphoma subtypes, and to evaluate whether PD-1 and PD-L2 expresion have impact on prognosis. Method: For this purpose, pre-treatment lymph node biopsy specimens of 92 patients [25 Hodgkin lymphoma (HL) and 67 non-Hodgkin lymphoma (NHL)] have been stained with monoclonal antibody immunstains of PD-1 and PD-L2. Results: The overall expression rate of PD-1 was 76% and 82.1% in patients with HL and NHL, respectively. PD-L2 expression rate was weak in both HL and NHL cases. Since we have evaluated whether there is a correlation between immunohistochemistry (IHC) results and survival of patients with HL and NHL, we couldn’t demonstrate a meaningful evidence that these markers have an impact on prognosis. Conclusions: We conclude that the role of PD-1 pathway can be demonstrated by IHC. If IHC markers might be standardized in the future, especially a cutoff that defines a clinically significant positive and predictive value, may help identifying patients more likely to benefit from anti-PD-1 therapies.

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