Loss of Acetylcholinesterase in Human Erythrocytes Treated with Trypsin, Papain or Bromelin: its Relationship with Susceptibility to Acid Lysis in vitro

YACHNIN and his associates were able to demonstrate that normal human red cells treated with various proteolytic enzymes, cholera vibrio filtrate, influenza virus and periodate ion, became susceptible to acid lysis in compatible human serum like paro,xysmal nocturnal haemoglobinuria (PNH) red cells ( Y a c h , Laforet and Gardner, 1961; Y a c h and Gardner, I 96 I a, b) . On the other hand, it has been found by several groups of workers (de Sandre, Ghiotto andMastella, 1956b; de Sandre andGhiotto, 1958,1960; Auditore and Hartmann, 1959; Metz, Bradlow, Lewis and Dacie, 1960) that PNH red cells susceptible to acid lysis (i.e. giving a positive Ham test) have a remarkable deficiency of stromal acetylcholinesterase (AchE) activity. This enzyme deficiency is not a consequence of dubition: the almost complete inhbition of normal human red cells AckE with diisopropylfluorophosphonate does not reduce their irz vivo survival (Perona, Ghiotto, Scandellari and Frezza, 1963). In order to clarify the relationship between stromal AchE activity and red-cell susceptibhty to acid lysis, we are conducting an investigation of the behaviour of these phenomena in normal erythrocytes treated with the various agents used by Yachnin and his associates. In the present paper we report the results obtained in red cells incubated with proteolytic enzymes: trypsin, papain and bromelin. Some of the data concerning trypsinized red cells have already been published elsewhere (Perona, de Sandre and Gbotto, 1963).