Fig. 4.

Ligation to flask-coated hIgG1 could reverse the suppressive effects of IL-6 + GM-CSF-induced MDSC on T cell proliferation. Total PBMC were isolated from peripheral blood of 3 healthy donors, plated in regular flasks or hIgG1-coated flasks (5 × 10⁵/mL) supplied with or without 10 ng/mL IL-6 and 10 ng/mL GM-CSF and cultured for 7 days. Then cells were harvested and surface markers were analyzed by flow cytometry. a Representative figure showing expression levels of HLA-DR on CD33⁺ myeloid cells from the indicated conditions. CD33⁺ cells were also isolated by FACS sorting and co-cultured with CFSE-labeled autologous T cells (10⁵ cells/well) at a 1:2 ratio. T cell stimulation was provided by anti-CD3/CD28 magnetic beads (bead: cell = 1:1). CFSE dilution was analyzed by flow cytometry for T cell proliferation after 3 days. b Summary data of proliferation of T cells co-cultured with CD33⁺ cells from the above cultures is shown. Proliferation of T cells in each condition was normalized to the matched T cell alone condition (100 %). The graph presents the mean ± SEM from 3 different healthy donors. Statistical significance was determined by one-way ANOVA followed by Tukey multiple comparison test. *p < 0.05. c Summary data showing expression level of surface CD16, CD32a and CD32b on CD33⁺ myeloid cells from the indicated conditions