Myeloid derived suppressor cells are numerically, functionally and phenotypically different in patients with multiple...

Area of Science:

• Immunology
• Hematology
• Oncology

Background:

• Myeloid-derived suppressor cells (MDSCs) are immune-suppressive cells implicated in various malignancies.
• MDSCs are a heterogeneous population with distinct granulocytic (G-MDSC) and monocytic (M-MDSC) subsets.
• Their role in multiple myeloma (MM) pathogenesis and immune evasion requires further characterization.

Purpose of the Study:

• To characterize MDSC populations in patients with multiple myeloma (MM).
• To investigate the impact of MDSCs on immune cell function, including T cell regulation and lymphocyte proliferation.
• To assess the effect of G-CSF treatment on MDSC levels in MM patients.

Main Methods:

• Phenotypic characterization of MDSCs using flow cytometry (CD33, CD11b, HLA-DR, CD15, CD14).
• Assessment of MDSC-induced regulatory T cell (Treg) generation.
• In vitro lymphocyte proliferation assays using CFSE tracking.
• Analysis of MDSC levels in peripheral blood and stem cell collections before and after G-CSF administration.

Main Results:

• A significant increase in G-MDSCs was observed in the blood of patients with progressive MM.
• Flow-sorted MDSCs from MM patients induced Treg generation.
• MDSCs from both MM patients and controls exhibited dose-dependent inhibition of lymphocyte proliferation.
• G-CSF administration increased peripheral blood MDSCs and their concentration in stem cell collections in MM patients.

Conclusions:

• MDSCs, particularly G-MDSCs, are elevated in progressive MM and contribute to immune suppression.
• MDSCs play a role in inhibiting lymphocyte proliferation and promoting Treg generation in MM.
• MDSCs accumulate in peripheral blood and stem cell collections following G-CSF treatment, potentially exacerbating immune dysfunction in MM patients.