Effects of Human Chorionic Gonadotropin on Differentiation and Functional Activity of Myeloid-Derived Suppressor Cells

The effect of recombinant human chorionic gonadotropin (hCG) at pregnancy-appropriate concentrations (10 and 100 IU/mL) on differentiation and functional activity of myeloid-derived suppressor cells (MDSCs) was studied. The object of the study was isolated CD11b⁺ cells that were converted to the MDSC phenotype by two-step activation with GM-CSF cytokines, IL1β and lipopolysaccharide (LPS). After a week of cultivation, the total MDSC level was determined considering the subpopulations M-MDSC and PMN-MDSC, the expression of arginase-1 (Arg1) and indoleamn-2,3-dioxydiogenase (IDO) in these cells, as well as the cytokine profile in cell culture supernatant. It was shown that hCG increased the total number of MDSCs, and its lower concentration (10 IU/mL) contributed to the differentiation of the M-MDSC subpopulation. hCG did not affect the expression of IDO expression in MDSCs, but there was a tendency to increase IDO expression under the influence of hCG at a concentration of 10 IU/mL. CD11b⁺ cells converted to the MDSC phenotype had a low Arg 1 content, making it impossible to evaluate the effect of the hormone on the expression of this enzyme. Evaluation of the cytokine profile by multiplex analysis showed that hCG did not modulate cytokine production in the culture of CD11b⁺ cells converted the MDSC phenotype. This is the first time that hCG has been shown to induce differentiation of MDSCs.