HDGF strongly reduces HLA-DR expression in human CD14⁺ monocytes and renders them immunosuppressive. Human CD14⁺ monocytes obtained from healthy volunteer blood donors were cultured with or without HDGF. (A) Representative histograms showing the reduction of HLA-DR when monocytes are cultured with HDGF (control monocytes are in red, HDGF-treated monocytes are purple). (B) Graph showing the percent inhibition of HLA-DR expression normalized to the levels of the control monocyte samples. (C) Representative T-cell proliferation histograms showing a significant reduction of T-cell proliferation when cocultured with HDGF-treated (HDGF-tr) monocytes. (D) Graph showing the percentage of dividing T cells in each condition. Means ± SD are shown (n = 4). *P < .001. Data shown in panels (B) and (D) represent the average values obtained from 4 independent experiments.