Erythroid progenitors in paroxysmal nocturnal haemoglobinuria

In vitro colony formation of bone-marrow erythroid progenitor cells in patients with paroxysmal nocturnal haemoglobinuria (PNH) was examined. The numbers of early and late erythroid progenitors (BFU-E and CFU-E) showed wide variations; two cases out of eight cases of PNH showed decreased erythroid colony formation, but other cases showed normal or rather increased colony formation of BFU-E and CFU-E. The number of erythroid progenitors in patients with PNH may be related to the marrow cellularity.