Expression and Significance of PD-1, PD-L1 and PD-L2 in T Cell Subsets and Myeloma Cells in Newly Diagnosed Multiple Myeloma Patients

Objective To investigate the expression of PD-1 and PD-L1/2 in T cell subsets and myeloma cells in the bone marrow from newly diagnosed multiple myeloma (NDMM) patients and their relation with clinical features.

Methods We collected the bone marrow and clinical data of 22 NDMM patients and 18 cases of healthy controls. We sorted CD4⁺T cells, CD8⁺T cells and myeloma cells by flow cytometry, and observed the expression of PD-1 and PD-L1/2.

Results Compared with the control group, the proportion of CD8⁺T cells in the NDMM group was significantly higher, while the ratio of CD4⁺/CD8⁺ was significantly lower (both P < 0.05). The expression levels of PD-1 and PD-L2 in CD4⁺T cells in the NDMM group were significantly higher than those in the control group (both P < 0.05). The expression levels of PD-1, PD-L1 and PD-L2 in T cell subsets and myeloma cells of NDMM patients were not correlated with the gender, age, immune typing, Durie-Salmon stage and subtypes, ISS stage or mSMART3.0 stratification (both P > 0.05).

Conclusion Most of MM patients suffering immune abnormality, which may be associated with the mutual immunosuppressive effects between T lymphocytes and plasma cells which expressing PD-1 and PD-L1/2.