Expression of programmed cell death ligand-1 protein in germinal center B-cell-like and non-germinal center B-cell-like subtypes of diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma worldwide. However, there is still limited information on the expression of programmed cell death ligand-1 (PD-L1), a type 1 transmembrane protein of immunoglobulin B7/CD28 in the DLBCL subtypes. The present study aimed to identify the expression of PD-L1 in germinal center B-cell-like (GCB) subtype and non-germinal center B-cell-like (non-GCB) subtype of DLBCL. A total of 40 patient samples (formalin-fixed paraffin-embedded tissues) consisting of 20 cases of GCB subtype and 20 cases of non-GCB subtype of DLBCL were examined. The PD-L1 protein expressions were evaluated by using immunohistochemical staining in the tumor cells. The results showed a statistically significant difference (P=0.003) between the expression of PD-L1 in the GCB subtype and the non-GCB subtype of DLBCL. PD-L1 expression in the tumor cells were observed in 13 cases (65%) of non-GCB subtype and in three cases (15%) of the GCB subtype of DLBCL. In conclusion, it was found that the expression of PD-L1 protein in the tumor cells of the non-GCB subtype of DLBCL was significantly higher as compared with the tumor cells of the GCB subtype of DLBCL.