Colony formation by CD34⁺CD59⁺ and CD34⁺CD59⁻ cells derived from BM of patients with PNH. (A) Flow cytometric analysis of a BM sample used for fluorescence-activated cell sorting. (B and C) Results of sorting for CD34⁺CD59⁻ cells (B) and CD34⁺CD59⁺ cells (C). (D) Colony formation by CD34⁺CD59⁺ and CD34⁺CD59⁻ cells. After sorting, cells were placed in methylcellulose supplemented with growth factors and were cultured for 14 days, and colonies with 50 or more cells were scored. Bars represent erythroid (black) and myeloid (white) colony formation by 2 patients with PNH. Sorted cells were plated in duplicate dishes. For fluorescence-activated cell sorting analysis, cells from two plates were pooled. (E) Flow cytometric analysis of progeny derived from cultures of CD34⁺CD59⁺ and CD34⁺CD59⁻ cells. Cells were washed out from methylcellulose cultures and stained with anti-CD59 MoAb. Log red fluorescence intensity versus cell number is plotted.