Diurnal Fluctuation of Leukocyte G6PD Activity. A Possible Explanation for the Normal Neutrophil Bactericidal Activity and the Low Incidence of Pyogenic Infections in Patients with Severe G6PD Deficiency in Israel

Acute hemolytic anemia associated with red blood cell (RBC) glucose-6-phosphate dehydrogenase (G6PD) deficiency is commonly encountered in the Mediterranean basin. Nevertheless, concomitant clinical evidence of white blood cell G6PD deficiency is extremely rare in Israel. This study sought to assess simultaneously levels of G6PD activity in polymorphonuclear leukocytes (PMN) and in red blood cells (RBC) of patients with G6PD deficiency, including full-term newborn infants. In PMN, the correlation between G6PD activity, hexose monophosphate shunt activity, and superoxide anion release was evaluated. In G6PD-deficient patients, a parallel and significantly decreased G6PD activity was found in neutrophils (range of activity 0-4.5 IU/10⁶ PMN) and erythrocytes (range of activity 0-1.8 IU/g Hb), compared with healthy controls (5-23 IU/10⁶ PMN and 2.4-6.4 IU/g Hb, respectively). A positive correlation was found in PMN between the levels of G6PD activity, hexose monophosphate (HMP) shunt activity, and superoxide anion release (p < 0.01). Nevertheless, all patients' bactericidal activity of neutrophils remained in the range of healthy controls. Although many episodes of acute hemolytic anemia were recorded, no increased incidence of pyogenic infections was observed in any group of patients investigated. Neutrophil and erythrocyte G6PD levels were re-assessed in some of these patients several times a day. A significant diurnal fluctuation of the enzyme activity was found. It is speculated that the patients produce fluctuating daily quantities of NADPH, sufficient to initiate the neutrophil respiratory burst and to achieve normal bactericidal activity, necessary to prevent the development of microbial infections.