Effect of CD3×CD123 DART on normal CD34⁺ progenitor cells. Cord blood cells from 3 healthy donors were incubated with DARTs for either (A) 4 hours or (B) 18 hours and plated in methylcellulose-based medium. Colonies were scored on day 7. Error bars represent the SD of duplicate plates. (C) Purified CD34⁺ progenitors and CD14⁺CD123⁺ monocytes from a healthy donor mobilized peripheral blood product (n = 2) were incubated with DARTs and autologous T cells for 18 hours. Cell survival was determined by flow cytometry.