Plasmapheresis in paroxysmal nocturnal hemoglobinuria aplastic crisis: clinical improvement and in vitro demonstration of plasma inhibitory activity on erythroid stem cells.

Plasmapheresis was used in a 51 year old woman with known PNH and aplastic crisis unresponsive to conventional treatment. A clinical and laboratory improvement was noted and an in vitro inhibition of BFU-E's obtained from patient's peripheral blood mononuclear cells was observed when autologous plasma or serum were added to cultures. The beneficial effect of plasmapheresis is though to be to the elimination of a plasma inhibitory factor responsible for the aplastic crisis in this PNH case that exerts its action to the committed erythroid progenitors as well.