Erythroid cell growth, maturation, frequencies of macrophage during the second phase of erythroid cell culture. (A) Erythroid cell numbers were counted on days 0, 2, 3, 4, 5, 6, and 7 of phase II. Solid line indicates the mean values of cell numbers of the 14 individuals with HbF less than 0.6%. Dashed line represents the mean cell numbers of the 12 individuals with HbF levels of 0.8% to 1.8%. Error bars refer to the SD. (B) Percentages of erythroid cells and GPA-positive cells on day 5 of phase II erythroid cells (CD71pos + CD71^posGPA^pos + GPA^pos cells). (C) Representative cytospins of erythroid cell cultures on day 5 of phase II from 2 different individuals (i, iii) in HPFH and control (ii,iv) groups. The cytospins were stained with modified Wright-Giemsa. Arrows indicate the macrophages. (D) Percentage of macrophages of the total number of cells (400 cells counted) on day 5 of phase II.