British journal of haematology
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The results of cytological and ultrastructural analysis of erythroid burst colonies derived from the peripheral blood of two patients with HEMPAS have been compared to those obtained in normal controls. Using the plasma clot technique, in studies on 10 subjects we confirmed that most of the colonies consisted or erythroblasts with a synchronous and normal maturation involving a wave of nuclear extrusion at day 13. In contrast, the majority of well-haemoglobinized colonies from HEMPAS consisted of numerous bi- or multinucleated erythroblasts displaying the supplementary double membrane beneath their plasma membrane. ⋯ These cells were unable to mature and subsequently lysed. Thus dyserythropoiesis occurred in culture both at early and late stages of maturation. These studies clearly demonstrate that HEMPAS is a disorder resulting from defective erythroid committed cells.