Background: Tumor-associated macrophages (TAMs) are originated from circulating mononuclear cells in peripheral blood. They result from the recruitment of tumor cells and are a vital constituent of the tumor microenvironment. TAMs may be involved in the immunological escape of vicious clonal plasma cells (PC) in the bone marrow (BM) of sufferers with myeloma.Methods: From March 2020 to January 2021, 28 healthy controls (HC) and 86 multiple myeloma (MM) (53 newly diagnosed MM [NDMM] and 33 remissions) patients were enrolled as objects of the study. The expression of TAMs in the BM, CSF1 on CD138 + cells, and CSF1R on macrophages were detected by the method of flow cytometry, and the expression of PD-1 on CD8 + T cells and PD-L1 on TAMs were also done. Bone marrow mononuclear cells (BMMNCs) were extracted and cultured into TAMs, CD8 + T cells were sorted by magnetic beads and cultured, a coculture system was established and different inhibitors were added.The expression of the perforin and granzyme B was detected by flow cytometry. Results:The percentage of TAMs in NDMM group (61.49 ± 2.176%) increased when compared with remission (23.08 ± 1.699%, p < 0.001) and HC group (17.95 ± 1.865%, p < 0.001), and TAMs decreased after adding CSF1R inhibitor.Moreover, the expression of CSF1 on CD138 + cells increased significantly in NDMM group (17.090 ± 0.9156%) than remission (8.214 ± 0.5911% p < 0.001), and HC group (5.257 ± 0.6231%, p < 0.001), and CSF1R on macrophages increased significantly in NDMM group (58.78 ± 2.286%) than remission (20.74 ± 1.376%, p < 0.001) and HC group (17.42 ± 1.081%, p < 0.001). The expression of PD-1 on CD8 + T cells in NDMM group (32.64 ± 2.982%) increased than remission (20.35 ± 2.335% p < 0.01) and HC group (17.53 ± 1.349%, p < 0.001), and PD-L1 on TAMs also increased in NDMM group (50.92 ± 2.554%) than remission (20.02 ± 1.893%, p < 0.001) and HC group (13.08 ± 1.289%, p < 0.001). When

Aplastic anemia (AA) is a primary disorder of severe bone marrow failure characterized by pancytopenia. The pathogenesis of AA is closely related to T cell hyperfunction. Abnormal telomere shortening of bone marrow mononuclear cells which has been reported in AA not only lead to genomic instability and apoptosis but also regulate T cells immunity to antigen. Interestingly,lymphocytes with shorter telomere length have undergone apoptosis escape in autoimmune disease. In our study, the relative telomere length (RTLs) of CD3+, CD3+CD4+, CD3+CD8+, CD19+ and CD34+ cells were investigated in 14 untreated AA patients and 32 controls. The RTLs of CD3+,CD3+CD4+ and CD3+CD8+T lymphocytes were shorter than those of the controls. Meanwhile, no differences in CD19+B and CD34+ cells were found between AA and controls. A change in telomere length may be involved in the pathogenesis of AA and could be considered as a predictive biomarker for the diagnose of AA. Disclosures No relevant conflicts of interest to declare.