Figure 1.
Figure 1. IL-20 specifically increases multipotential progenitors in vitro. (A) IL-20 increases numbers of larger-sized colonies containing erythrocytes, megakaryocytes, granulocytes, and monocytes. Human CD34+ bone marrow cells were cultured in methylcellulose medium containing 50 ng/mL SCF and 1 U/mL EPO with or without 200 ng/mL IL-20. Colonies represented control (i) or rhIL-20–containing (ii) cultures. Aiii and iv are Wright-Giemsa–stained cells from individual colonies picked from rhIL-20–containing cultures. Arrows in panel Aiii point to megakaryocytes at × 200 original magnification. Granulocytes or monocytes were detected at higher magnification (× 400 original magnification) and are marked by arrows in panel Aiv. (B) IL-20 enhances CFU-GEMM but not BFU-E and CFU-GM numbers in human bone marrow CD34+ culture in the presence of EPO, SCF, GM-CSF, and IL-3. Increases of CFU-GEMM were also observed when IL-20 was used in combination with EPO and SCF. Combining IL-20 with G-CSF, GM-CSF, or M-CSF had no effect on CFU-GM or CFU-M. Data represent mean ± SD from triplicate experiments. Similar results were obtained from 12 individual bone marrow samples. (C) IL-20 enhances CFU-GEMMs in cord blood. Human cell studies were approved by the Institutional Review Board of Indiana University. Human cells were assessed after the recovery of low-density (less than 1.077 g/cm3) cells, magnetic-bead–separated CD34+ cells, or FACS sorted CD34+hi cells. Data represent means ± SD from triplicate experiments. Similar results were obtained in 10 different experiments. (D-E) IL-20 had no effect on CFU-Meg colonies but increased CFU-Meg/BFU-E mixed colonies. Bone marrow CD34+ cells were assayed for megakaryocyte-containing colonies in serum-free, collagen-based media containing various cytokines. The stimulus was 50 ng/mL TPO, 50 ng/mL SCF, and 2 U/mL EPO. Clusters of 3 or more CD41+ cells were scored as CFU-Meg. Colonies containing megakaryocytes and erythroid cells were scored as CFU-MIX (right panel). Each column corresponds to the mean ± SD of duplicate cultures, and each culture contains 2 repeats (n = 4). *P < .02 compared with respective controls without rhIL-20, based on 2-tailed Student t test.

IL-20 specifically increases multipotential progenitors in vitro. (A) IL-20 increases numbers of larger-sized colonies containing erythrocytes, megakaryocytes, granulocytes, and monocytes. Human CD34+ bone marrow cells were cultured in methylcellulose medium containing 50 ng/mL SCF and 1 U/mL EPO with or without 200 ng/mL IL-20. Colonies represented control (i) or rhIL-20–containing (ii) cultures. Aiii and iv are Wright-Giemsa–stained cells from individual colonies picked from rhIL-20–containing cultures. Arrows in panel Aiii point to megakaryocytes at × 200 original magnification. Granulocytes or monocytes were detected at higher magnification (× 400 original magnification) and are marked by arrows in panel Aiv. (B) IL-20 enhances CFU-GEMM but not BFU-E and CFU-GM numbers in human bone marrow CD34+ culture in the presence of EPO, SCF, GM-CSF, and IL-3. Increases of CFU-GEMM were also observed when IL-20 was used in combination with EPO and SCF. Combining IL-20 with G-CSF, GM-CSF, or M-CSF had no effect on CFU-GM or CFU-M. Data represent mean ± SD from triplicate experiments. Similar results were obtained from 12 individual bone marrow samples. (C) IL-20 enhances CFU-GEMMs in cord blood. Human cell studies were approved by the Institutional Review Board of Indiana University. Human cells were assessed after the recovery of low-density (less than 1.077 g/cm3) cells, magnetic-bead–separated CD34+ cells, or FACS sorted CD34+hi cells. Data represent means ± SD from triplicate experiments. Similar results were obtained in 10 different experiments. (D-E) IL-20 had no effect on CFU-Meg colonies but increased CFU-Meg/BFU-E mixed colonies. Bone marrow CD34+ cells were assayed for megakaryocyte-containing colonies in serum-free, collagen-based media containing various cytokines. The stimulus was 50 ng/mL TPO, 50 ng/mL SCF, and 2 U/mL EPO. Clusters of 3 or more CD41+ cells were scored as CFU-Meg. Colonies containing megakaryocytes and erythroid cells were scored as CFU-MIX (right panel). Each column corresponds to the mean ± SD of duplicate cultures, and each culture contains 2 repeats (n = 4). *P < .02 compared with respective controls without rhIL-20, based on 2-tailed Student t test.

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