Inactivation of Erythrocyte Acetylcholinesterase by Penicillin

Abstract

ACETYLCHOLINESTERASE (ACHE) activity appears to be located at the outer surface of the human erythrocyte¹. We have previously shown that ACHE activity is reduced in newborn children affected with ABO haemolytic disease². A similar defect has been detected in erythrocytes of patients with paroxysmal nocturnal haemoglobinuria (PNH)³. Watson⁴ has reported that in contrast to normal erythrocytes, those from patients with PNH do not bind penicillin G. In an attempt to establish further similarities between the erythrocytes of infants with ABO disease and the cells of patients with PNH we tested penicillin-binding capacity. Using the technique described by Watson et al.⁵ with a highly sensitive strain of β-haemolytic streptococci as indicator, we could confirm the inability of PNH erythrocytes to bind penicillin but could not detect decreased binding by red cells from infants with ABO haemolytic anaemia compared with normal adult erythrocytes. Unexpectedly, when membranes from penicillin-treated red cells were tested for ACHE activity, significant inactivation was noted. This observation prompted an investigation of the effects of this antibiotic on erythrocyte ACHE activity. Additional indications for conducting these studies were the recent demonstrations of antipenicillin antibodies^6,7 and of in vivo coating of erythrocytes by penicillin⁸ in cases of haemolytic anaemia caused by administration of penicillin.