Effects of PEG-rHuMGDF associated with other cytokines on platelet production from CD34⁺ CD41⁺ cells. Marrow-derived CD34⁺ CD41⁺ cells were grown in serum-free conditions in the presence of 1 ng/mL PEG-rHuMGDF alone or combined with IL-3 (100 U/mL), SCF (50 ng/mL), and IL-6 (100 U/mL). Platelets were enumerated at day 7 of culture by flow cytometry. Asterisk denotes a significative difference (P < .05) in comparison with culture with 1 ng/mL PEG-rHuMGDF alone.