Effect of KL with and without Dex on erythroid cell growth and maturation. Left panels: growth curve from minibulk HPC erythroid cultures obtained from 10 healthy adults, 10 β-TI, and 10 β-TM PB patients supplemented or not with KL (100 ng/mL) or KL (100 ng/mL) plus Dex (10⁻⁸ M). Total cell number (mean ± SEM) starting from initial 5×10⁴ CD34⁺ cells/mL is shown. The differences between the normal and β-TI or β-TM control growth curves are highly significant by analysis of variance (P < .001). Right panels: kinetics of erythroid maturation observed in the same minibulk HPC cultures reported in left panels. The percentage (mean ± SEM values) of mature erythroblasts (late polychromatophilic + orthochromatic erythroblasts) is shown.