Differences between the Red Cell Acetylcholinesterase Defects of Paroxysmal Nocturnal Hemoglobinuria and of ABO Hemolytic Disease

A Review: Human Erythrocyte Acetylcholinesterase

“…No inhibitors of acetylcholinesterase could be found in patients with reduced enzyme activity [47] and no differences in regard to substrate specificity, pH profile, K m , effects of inhibitors [47,71] and of inactivators [42,43,46], and thermostability were found when enzyme from acetylcholinesterase-deficient erythrocytes was compared with that of normal cells. The report by Ferrone et al [29] that the reduced acetylcholinesterase activity of erythro- cytes from newborn infants with ABO disease was more resistant to heat denaturation than the enzyme activity of the cells from normal infants could not be confirmed in our laboratory.…”

“…Acetylcholinesterase activity, like the activity of many intracellularly located enzymes [12], gradually declines as the erythrocyte ages [47]. The relationship between the decline in activity and structural and functional alterations which determine the ultimate removal of the aged erythrocyte from the circulation have not been elucidated.…”

“…By comparison, a much more accelerated decrease in activity is seen in patients with reduced enzyme activity, either because of ABO hemolytic disease or because of autoimmune hemolytic anemia [49]. An exception to the rule that acetylcholinesterase activity declines as the circulating erythrocytes age, is seen in paroxysmal nocturnal hemoglobinuria [3,47]. In this condition, the activity is higher in the circulating older cells than in reticulocytes.…”

“…The dissociation between acetylcholinesterase activity and reticulocyte content in newborn infants becomes even more significant when viewed in the context of the activity of other erythrocyte enzymes. For example, the activities of the intracellularly located glucose 6-phosphate dehydrogenase [47] and inorganic pyrophosphatase [44] are increased not only in fractions containing the youngest cells but also in unseparated erythrocyte specimens from normal infants and from neonates with ABO disease [60]. These observations would exclude the possibility that the reduced acetylcholinesterase activity observed in ABO disease is the result of a preferential elimination from the circulation of younger cells which possess stronger A and B antigens, thereby leaving a cell population of older mean age [38].…”

Loss of Acetylcholinesterase Activity in Human Erythrocytes Treated with Cephalothin

“…The activity of this stromal enzyme is also reduced in patients with paroxysmal nocturnal hemoglobinuria (PNH) [5]. However, studies with red cells separated in accordance with their density revealed that in this disorder the enzyme distribution pattern was characteristically different than that found in ABO hemolytic disease [6]. Investigations undertaken to elucidate the pathophysiology of this enzyme defect have shown that alterations of ACHE activity can be produced by exposing normal erythrocytes to certain chemically-unrelated sub stances which interact with the red cell membrane [7][8][9].…”