Study of in Vitro Lysis of Paroxysmal Nocturnal Haemoglobinuria (PNH) and PNH‐like Red Cells

Summary. In paroxysmal nocturnal haemoglobinuria (PNH) the intensity of haemolysis obtained in the acidified‐serum and sucrose‐haemolysis tests—the two procedures most commonly used for the laboratory diagnosis of the disease—varies according to the red cells, serum and test used. The influence of these three variables has been investigated on both PNH and PNH‐like lysis, that is lysis of PNH cells and of normal red cells treated in vitro with the sulphydryl compound 2‐aminoethylisothiouronium bromide (AET). The conclusions, almost identical for PNH and AET lysis experiments, suggest that for the laboratory diagnosis of PNH: (1) it is advisable to use both tests in parallel; (2) sera to be used in the two tests should be selected; (3) for this selection AET cells can be employed when PNH cells are not available.