On the Mechanism of the In Vitro Production of Ham‐positive Red Cells by Sulphydryl Compounds: Role of pH and Free ‐SH Groups

Experiments were carried out in order to obtain high percentages of Ham‐positive red cells (HPRC) from normal human red cells incubated with various ‐SH containing compounds and to evaluate the role of the free ‐SH groups in these sulphydryl compounds and of the red cells themselves in the HPRC‐producing process. The sulphydryl compounds producing HPRC were all far more effective at pH 9 than at lower pH values; they became ineffective if their ‐SH groups were blocked. Sulphydryl‐inhibited red cells maintained their susceptibility to become HPRC suggesting that sulphydryl compounds display their damaging activity other than upon the free ‐SH groups of the red cell membrane. HPRC have been obtained using 2‐mercaptoethylamine, 2‐mercaptoethanol or 3‐mercaptopropionic acid.