Yields of CD41⁺PI⁺ cells in cultures containing control or ITP plasma collected when patients were in thrombocytopenic phase. Umbilical cord blood MNCs were cultured for 8 days in the presence of rhTPO and either control or ITP plasma. The ITP plasma samples were classified into 4 subgroups as described in the text. (A) The yields of CD41⁺PI⁺cells in the cultures were determined with the use of the 2-color flow cytometric technique. Results were presented as the percentage of the controls (means ± SDs). The yields of CD41⁺PI⁺cells in groups IIb/IIIa/Ib and Ib culture were significantly lower than that of the control (P < .001). (B) The yields of CD41⁺PI⁺cells in the cultures containing individual patient plasma from 4 subgroups. The data were arranged from lowest yield to the highest.