discussion |
discussion |
conclusion |
MDSCs can be differentiated in vitro. According to the flow cytometry data, differentiation of BALB/c and Black-6 yields more G-MDSCs than M-MDSCs.
Black-6 MDSCs were differentiated using BALB/c 4T1 conditioned medium which demonstrates that cross strain differentiation can occur. Both Black-6 and BALB/c MDSCs have the same cytokines, but the receptors on the cell surfaces are different. This assay suggests that precursor MDSCs can be differentiated despite cytokine concentration. A cell type with Ly6ChiLy6Ghi phenotype was observed. Review of literature suggests that MDSCs with this phenotype have not been yet characterized perhaps showing that a new cell type was discovered. CD11b+Ly6ChiLy6Ghi phenotype may be expressed by G-MDSCs that have high numbers of Ly6C receptors due to high plasticity of MDSCs. An IL-6 ELISA reported a relatively small amount of IL-6 present in BALB/c 4T1 conditioned medium. A proportional relationship between concentration of IL-6 and time was found. MDSCs differentiated more at a high and low concentration of IL-6 neutralizing antibody. The high percentage of MDSCs differentiated at a high concentration of IL-6 (33.9% in G-MDSCs and 55.3% in M-MDSCs) occurred likely because at high concentrations of neutralizing antibody cause cell activation rather than receptor deactivation. IL-6 peptide concentration is proportional to amount of MDSCs indicating that IL-6 is an important factor in MDSC differentiation. |
The relatively new technique of MDSC differentiation in vitro can be used to produce large amounts of MDSCs in order to further study and characterize the cells. Cells with the CD11b+ Ly6chi Ly6ghi phenotype were observed in all differentiation assays. The combination with CD11b and Ly6c or Ly6g indicated the cell type is a MDSC, so the double positive cells are assumed to MDSCs. Further research in characterization of this cell type ought to be performed. Gene editing technique such as CRISPR or RNAi could be used to inhibit the production of the interleukin-6 receptors and determine whether MDSCs differentiation is dependent on IL-6. Additional research will be conducted by Dr. Nicholas Pullen and David Lyons at the University of Northern Colorado to further characterize myeloid-derived suppressor cells.
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