Age-dependent increase in green autofluorescence of blood erythrocytes

Abstract

Green auto-fluorescence (GAF) of different age groups of mouse blood erythrocytes was determined by using a double in vivo biotinylation (DIB) technique that enables delineation of circulating erythrocytes of different age groups. A significant increase in GAF was seen for erythrocytes of old age group (age in circulation more than 40 days) as compared to young erythrocytes (age less than 15 days). Erythrocytes are removed from blood circulation by macrophages in the reticulo-endothelial system and depletion of macrophages results in an increased proportion of aged erythrocytes in the blood. When mice were depleted of macrophages for 7 days by administration of clodronate loaded liposomes, the overall GAF of erythrocytes increased significantly and this increase could be ascribed to an increase in GAF of the oldest population of erythrocytes. Using the DIB technique, the GAF of a cohort of blood erythrocyte generated during a 5 day window was tracked in vivo. GAF of the defined cohort of erythrocytes remained low till 40 days of age in circulation and then increased steeply till the end of the life span of erythrocytes. Taken together our results provide evidence for an age dependent increase in the GAF of blood erythrocytes that is accentuated by depletion of macrophages. Kinetics of changes in GAF of circulating erythrocytes with age has also been defined.

Serum Pantetheinase/Vanin Levels Regulate Erythrocyte Homeostasis and Severity of Malaria

“…This autofluorescence is associated with aging and has been attributed to the accumulation of Hb degradation products. 42,43 Quantification of AF 520 RBCs by flow cytometry ( Figure 6F) showed that they were enriched in SHIVA but also PA low mice, showing that this phenotype is dissociated from the SHIVA genetic background and associated with mice with PA low . Because Sox17 has been shown to regulate fetal hematopoiesis, we tested whether this AF 520 phenotype might be cell autonomous.…”

A Double in vivo Biotinylation Technique for Objective Assessment of Aging and Clearance of Mouse Erythrocytes in Blood Circulation

“…In an earlier report, enhanced PS externalization was demonstrated on aged populations of erythrocytes using FITC-tagged annexin [4]. Although we could reproduce these results, we found that if phycoerythrin (PE)-tagged annexin was used to detect PS, no change in PS expression was found on aged erythrocytes [19].…”

“…Similarly, old erythrocytes are not significantly enriched in heaviest fractions (young/old ratios 0.48 and 0.65, Mouse erythrocytes were biotinylated as per Protocol B and fractionated on a Discontinuous PDG with five layers of densities .,0650 ± 0.004, 1.0711± 0.006, 1.0782 ± 0.008, 1.0858 ± 0.004 and 1.0883 ± 0.003 g/ml prepared as described before [19]. Erythrocytes in different buoyant density fractions were stained with streptavidin-APC followed by flow cytometric analysis.…”

Experimental immunology Expression levels of CD47 on red blood cells during their storage in blood bank

“…A phenomenon like that can also play a role in long-stored units of non-leukoreduced RBCs presented now. During storage, residual leucocytes release cytokines, enzymes and other bioreactive molecules which can alter the RBC membrane and increase RBC adherence to endothelial cells [21,22].…”