In vitro differentiation of MDSC-like cells as a model for studying immunosuppressive mechanisms in pediatric B cell lymphoma.

Diffuse large B cell lymphoma (DLBCL) is an aggressive malignancy that is rarely manifested in pediatric patients, and research into the immunoregulatory environment present in the disease is limited due to the scarcity of patient samples. Myeloid-derived suppressor cells (MDSCs) are a population of immunosuppressive cells that expand in patients with DLBCL and interfere with T cell proliferation, therefore, dampening the host’s overall immune response. For the same reason, MDSCs compromise the effectiveness of CAR T cells, which are used as an alternative approach for treating B-cell malignancies. This study aims to evaluate the protocol for THP-1 cell line differentiation into MDSC-like cells using IL-4 and G-CSF-based treatment and to assess whether the resulting cells acquire a transcriptional profile consistent with immunosuppressive MDSCs. Differentiation was induced over seven days, and the functional profile of the cells was evaluated via RT-qPCR. Treated cells exhibited upregulation of immunoregulatory cytokines IL-6, IL-10, IL-12p40, and functional markers ARG1 and NOS2, alongside downregulation of TNF, reflecting the expected immunosuppressive phenotype. Unexpectedly, IL-1β was also upregulated, potentially reflecting culture-induced stress, cellular heterogeneity, or a context-dependent feature of MDSCs. These results indicate that THP-1 cells can be successfully differentiated into MDSC-like cells and support their use as an in vitro model for studying immunosuppressive mechanisms in pediatric DLBCL. However, comprehensive validation requires further functional and phenotypic characterization, including flow cytometry and lymphocyte proliferation assays, and optimization of cytokine concentrations and incubation conditions. This model provides a valuable platform for investigating tumor-immune interactions and for developing strategies to enhance the efficacy of immunotherapies such as CAR-T cells in pediatric patients with refractory DLBCL.