Number of cells generated from normal and IMF CD34⁺cell cultures. (A) The absolute total number of cells generated by normal, IMF, and PV CD34⁺ cells after 15 days of culture in the presence of maximal cytokine combination (100 ng/mL TPO and 100 ng/mL SCF) favoring megakaryocyte development. Each ▴ represents the result of a single experiment with specimens from different patients. The bar represents the mean number of values for each group. The total number of cells generated from CD34⁺ cells was significantly greater in IMF samples (n = 7) compared with normal samples (n = 4) and PV samples (n = 4) (P < .05). (B) The absolute number of CD41⁺ cells generated after 15 days in the same cultures. The numbers of CD41⁺ cells generated by IMF CD34⁺ cells was statistically greater than the numbers generated by normal CD34⁺ cells (n = 4) or PV CD34⁺ cells (P < .05). No significant difference (C) in the absolute numbers of cells or (D) the absolute number of CD41⁺ cells generated by the CD34⁺ cells obtained from patients with JAK2 617V>F–positive and –negative IMF was found (P > .05).