ERYTHROCYTE AGING: A DECREASE IN THE ANTIOXIDANT RESPONSE?

RACCA L; RUCCI A; LUJÁN M; COTORRUELO C; GARCÍA BORRÁS S; RACCA A; MILANI A; BIONDI C; ACOSTA L

Madrid - España

Congreso; XVII Regional Congress of the ISBT Europe; 2007

International Society of Blood Transfusion

Background: Red blood cell (RBC) aging is a complex process affected by immunological and biochemical parameters. Lipids and proteins oxidation by oxygen reactive species (ORS) generated by cellular metabolism is the most frequent membrane biomolecules modification. The antioxidant defenses consist of an enzymatic and a non enzymatic system. Aims: The objective of this work was to study the antioxidant response during RBC aging studying the metahemoglobin-NADH reductase (Hbi-R) and glucose-6-phosphate deshidrogenase (G6PD) activities. Methods: ACD anticoagulated blood samples from 15 O RhD+ volunteers´ donors were centrifuged to concentrate RBC to a hematocrit of 80%. Density separation was effected by short--duration, high speed centrifugation of these concentrated RBC. The top and bottom 10% fractions were removed and designated as Young (Y) RBC and Senescent (Se) RBC, respectively. The Glock and McLean method was used to determine the G6PD activity and the Board method was used to analyze the Hbi-R activity in soluble and membrane bound fractions. Comparisons statistical were performed by means of the t test for paired samples. Results: The G6PD activity in SeRBC (4.55 ± 1.46 UI G6PD/Hb) was significantly lower than that observed in YRBC (7.11 ± 1.44 UI G6PD/gHb; p < 0.0001). The activity of the membrane bound Hbi-R in SeRBC (441.27 ± 97.79 UHbi-R/mgProt) was significantly lower than that found in YRBC (491.73 ± 84.02 UHbi-R/mgProt; p < 0.005). No differences were found in the soluble fractions of both groups (SeRBC: 20.50 ± 2.64 UHbi-R/mgHb vs YRBC: 19.80 ± 2.22 UHbi-R/mgHb; p > 0.05). Conclusions: The results indicate that the antioxidant capacity during RBC aging is decreased due to a lower production of NADPH by G6PD that allow the regeneration of Hb from Hbi. The decrease in the activity of the membrane bound HBi-R would indicate a loss in the antioxidant process during RBC aging.