Blood Cells Of Different Ages Research Articles

Accounting for red blood cell accessibility reveals distinct invasion strategies in Plasmodium falciparum strains.

The growth of the malaria parasite Plasmodium falciparum in human blood causes all the symptoms of malaria. To proliferate, non-motile parasites must have access to susceptible red blood cells, which they invade using pairs of parasite ligands and host receptors that define invasion pathways. Parasites can switch invasion pathways, and while this flexibility is thought to facilitate immune evasion, it may also reflect the heterogeneity of red blood cell surfaces within and between hosts. Host genetic background affects red blood cell structure, for example, and red blood cells also undergo dramatic changes in morphology and receptor density as they age. The in vivo consequences of both the accessibility of susceptible cells, and their heterogeneous susceptibility, remain unclear. Here, we measured invasion of laboratory strains of P. falciparum relying on distinct invasion pathways into red blood cells of different ages. We estimated invasion efficiency while accounting for red blood cell accessibility to parasites. This approach revealed different tradeoffs made by parasite strains between the fraction of cells they can invade and their invasion rate into them, and we distinguish “specialist” strains from “generalist” strains in this context. We developed a mathematical model to show that generalist strains would lead to higher peak parasitemias in vivo compared to specialist strains with similar overall proliferation rates. Thus, the ecology of red blood cells may play a key role in determining the rate of P. falciparum parasite proliferation and malaria virulence.

Age-Dependent Acoustic and Microelastic Properties of Red Blood Cells Determined by Vector Contrast Acoustic Microscopy

Variations of the mechanical properties of red blood cells that occur during their life span have long been an intriguing task for investigations. The research presented is based on noninvasive monitoring of red blood cells of different ages performed by scanning acoustic microscopy with magnitude and phase contrast. The characteristic signature of fixed cells from groups of three different ages fractionated according to mass density is obtained from the acoustic microscope images, with the data represented in polar graphs. The analysis of these data enables the determination of averaged values for the velocities of ultrasound propagating in the cells from the different groups ranging from (1,681 ± 16) m s(-1) in the youngest to (1,986 ± 20) m s(-1) in the oldest group. The determined bulk modulus varies with age from (3.04 ± 0.05) GPa to (4.34 ± 0.08) GPa. An approach to determine for an age-mixed population of red blood cells, collected from a healthy person, the age of the individual cells and the age dependence of the cell parameters including density, velocity, and attenuation of longitudinal polarized ultrasonic waves traveling in the cells is demonstrated.

Cation transport and cell volume changes in maturing rat reticulocytes.

During maturation, reticulocytes lose membrane material, including transporters, and this is accompanied by a loss of cell water and volume. Here we determined a possible role of ion transport in adjusting cell volume during maturation. Reticulocytes and red blood cells of different ages were prepared from erythropoietin-treated rats by density gradient fractionation. Cell volume and ion transport were measured in freshly prepared cells and in reticulocytes during in vitro maturation. Reticulocytes had an increased K content and cell volume, whereas intracellular Na was decreased. All parameters approached whole blood values after 2 days in culture. Na-K pump was elevated in reticulocytes and decreased during maturation. Na-K-2Cl cotransport (NKCC) activity was lower in reticulocytes and was activated 8- and 20-fold by shrinkage and okadaic acid, respectively, whereas stimulation was barely detectable in high-buoyant density red blood cells. The ouabain- and bumetanide-insensitive Na flux in reticulocytes decreased on maturation. Most of it was inhibited by amiloride, indicating the presence of Na/proton exchange. Our results show that, although the Na-K-pump activity in reticulocytes is very much increased, the enhanced capacity of NKCC is essentially cryptic until stimulated. Both types of capacities (activities) decrease during maturation, indicating a possible loss of transport protein. The decrease was constrained to the period of reticulocyte maturation. Loss of transport capacity appears to exceed the loss of membrane surface area. Reticulocyte age-related changes in the net electrochemical driving force indicate that the increasing NKCC activity might contribute to the reduction in cell water.

Red blood cell age dependent modifications of inositol 1,4,5-trisphosphate

The level of inositol 1,4,5-triphosphate (Insl,4,5P 3) was determined in human and rabbit red blood cells of different ages. In human erythrocytes, fractionated by discontinuous density gradient centrifugation, Ins1,4,5,P 3 was 290 nM in the 0.3% low density (youngest) cells compared to values of 107 nM in the whole red blood cell population. A progressive increase in Ins1,4,5P 3 was then observed during erythrocyte aging from values of 63 nM in mature erythrocytes to 128 nM in the oldest cells. Determinations of Ins1,4,5P 3 in rabbit erythrocytes provided values of 180 nM. Phenylhydrazine was administered to three animals to induce reticulocytosis. Ins1,4,5P 3 in rabbit reticulocytes was significantly lower than in the whole red cell population, remained lower in young red blood cells and then increased to normal values during cell maturation. These results provide evidence for an increase of Ins1,4,5P 3 during red blood cell aging and could contribute to explain the age-dependent loss of deformability and of Ca 2+ homeostasis of these cells.

Analysis of density-fractionated rat red blood cells of different ages by partitioning in two-polymer aqueous phase systems

Rats were injected with radioactive iron and bled at different times thereafter. This gave rise to cell populations in which the bulk of labeled cells corresponded in age to the time elapsed between injection and bleeding. Such cell populations were centrifuged and the 7–10% least dense and the 7–10% most dense cells subjected to counter-current distribution in a charge-sensitive two-polymer aqueous phase system which fractionates cells on the basis of surface properties. While it is known that there is a tendency for cell density to increase with cell age and that rat red cells of different ages have characteristic partition ratios, we were able, by applying partitioning analysis to density-separated cells, to gather data not obtainable by use of either method alone. These include: (1) the demonstration of two very young cell populations having different surface properties in the most dense fraction; (2) the finding that in the least dense layer labeled mature erythrocytes (at least those labeled 18 days and beyond) and unlabeled red cells have overlapping distribution curves which indicate that the label in the top fraction can represent young or early middle-aged but never old cells; and (3) the presence, as judged by surface properties, of some middled-aged red cells, in addition to old cells, in the most dense cell layer.

Effect of surface modification of rat erythrocytes of different ages on their partitioning behavior in charge-sensitive two-polymer aqueous phases

Partitioning differences between cells in two-polymer aqueous phase systems originate from subtle differences between the surface properties of cells. Because of the exponential relation between the parameters affecting the partition ratio ( P) and the P itself, differences in membrane components suspected of affecting the differential partitioning of closely related cell populations cannot be directly established by conventional chemical assay techniques. In order to study the chemical nature of the components responsible for the age-related changes in surface properties of rat red cells we have devised an approach which uses a combination of isotopic labeling of erythrocyte subpopulations of distinct cell age with different enzyme and/or chemical treatments followed by countercurrent distribution in charge-sensitive two-polymer aqueous phase systems. These studies show that: (a) neuraminidase-susceptible sialic acid is not responsible for the cell age-related surface differences detected by partitioning; (b) the component(s) responsible for the cell age-related surface differences can be extracted (from aldehyde-fixed red cells) with ethanol or cleaved with dilute sulfuric acid. Our data are consistent with the hypothesis that ganglioside-linked sialic acid is the chemical moiety responsible for the cell charge-associated surface differences among rat blood cells of different ages.

Oxygen transfer resistance as a criterion of blood ageing

A modified rapid flow technique was used in order to measure the rate of oxygen transfer out of red blood cells of different ages. The oxygen transfer rate is expressed as a mass transfer coefficient determined in blood samples that were stored in the local blood bank for different periods of time. The results show that the resistance to oxygen transfer increases with age. This suggests that the decrease in the quality of stored blood is due, partially at least, to changes in the red blood cell membrane. The method can also provide a functional way of testing the quality of stored blood.

The effect of neuraminidase on the relative surface charge-associated properties of rat red blood cells of different ages

Approx. 70% of the sialic acid on the rat erythrocyte surface is susceptible to cleavage by neuraminidase ( Vibrio cholerae). Neuraminidase treatment results in a reduction in the partition coefficient ( K) of the red cells in a charged dextran-poly(ethylene glycol) aqueous phase system and in the electrophoretic mobility of the cells. Countercurrent distribution of rat neuraminidase-treated erythrocytes, containing 59Fe-labeled mature red cells of distinct age, indicates that (a) the electrophoretic mobilities of red cells in different cavities along the extraction train increase with increasing K, as is the case with untreated erythrocytes, and (b) the cell age-related differences in surface charge-associated properties are neither eliminated nor altered by the enzyme action.

Subfractionation of cell populations by partitioning in dextran-poly (ethylene glycol) aqueous phases

Partitioning of cells in dextran-poly(ethylene glycol) aqueous two-phase systems depends on the interaction between the surface properties of the cells and the physical properties of the phases. The latter can be manipulated to a considerable extent by selection of polymer concentrations and ionic composition and concentration. If salts (e.g., phopshate) are used that have an unequal affinity for the two phases, an electrostatic potential difference between the phases results and, at appropriately high polymer concentrations, the partition coefficient of cells is determined predominantly by membrane charge-associated properties. By “balancing” the magnitude of the electrostatic potential difference against that of the interfacial tension (primarily a function of polymer, but also phosphate, concentrations) one can obtain phase systems that give usable partition coefficients for most cell populations (1). In work under way in our laboratory on the effects of different chemical and enzymatic modifications on the relative surface properties of rat red blood cells of different ages, we have now found that certain phase compositions did not resolve such treated cell subpopulations while other phase compositions did. Thus not all charged phase systems in which cell populations as a whole have usable partition coefficients are equally capable of detecting or subfractionating cell subpopulations. It is therefore essential, before drawing conclusions on the nonseparability of cell subpopulations, to test cell separability in charged phase systems of different compositions if the system initially chosen does not afford a subfractionation.

Studies on the mechanism of erythrocyte aging and destruction I. Separation of rat erythrocytes according to age by ficoll gradient centrifugation

A 22–34% linear Ficoll gradient is described for use in separating red blood cells of different ages. Newly synthesized, 59Fe-labeled red cells were found in the top fractions of the gradient, and these cells moved down toward the lower part of the gradient as they became older. The Ficoll gradient method gave a higher resolution compared to existing published methods. Red blood cells with increasing density, increasing sphericity and decreasing volume were separated by the Ficoll gradient method. The protein content remained constant in red cells up to about two weeks of age, and then showed a trend to decrease with age. Changes in density, shape, volume, and probably protein content, are characteristics of aging red cells.

Partition and countercurrent distribution of erythrocytes and leukocytes from different species

1. 1. The partition of red blood cells, white blood cells and platelets from a number of different species in aqueous, dextran-polyethylene glycol 2-phase systems was studied. The partitition coefficients of these cells were found to be species dependent; they provide, in some cases, a method for the separation of leukocytes from erythrocytes by countercurrent distribution. 2. 2. The separability of red blood cells from white blood cells by countercurrent distribution is illustrated for rabbit and for rat. The partitition coefficients of their red and white cells are sufficiently different that a separation is feasible. Distribution curves of erythrocytes and leukocytes from these two species are presented as confirmation of the partition studies. Since red blood cells of different ages are separated by countercurrent distribution [11], it follows that by appropriate choice of phase system and species one can obtain red blood cells of different ages free of white blood cells in one operation. 3. 3. It is also shown that the sequence of partition coefficients for erythrocytes and platelets from a number of species is similar. This may be fortuitous or indicate a similarity of those surface properties which determine the partition of cells in these phase systems. 4. 4. Countercurrent distribution of white blood cells from lamb (and rabbit but not human) results in a 2-peak curve. Preliminary examination of the lamb cells in the different cavities of the extraction train indicates the presence of both granulocytes and lymphocytes under both curves. It is possible (although by no means established) that we have resolved two populations of granulocytes and two populations of lymphocytes. Among other possibilities is that intact and damaged leukocytes have been separated. Studies with white cells are being continued. 5. 5. A few remarks on phase systems and the possible relation between these and the cell characteristics which determine the partition of cells are included.

Effects of DEAE-dextran on the partition of red blood cells in aqueous dextran-polyethylene glycol two-phase systems

Red blood cells of different ages and at least two populations of reticulocytes can be separated by countercurrent distribution in one of the buffered, aqueous two-phase systems containing dextran and polyethylene glycol. Rabbit red cells which are the most extensively studied in the current literature do not partition in these systems because of their low surface charge. We now report that the addition of small quantities of the cationic polymer DEAE-dextran to some of the previously used phase systems containing non-ionic polymers permits the distribution of low-charged cells (as exemplified by rabbit red cells). As a consequence we have been able to resolve rabbit red cells of different ages by countercurrent distribution. While dog red cells (which have a high surface charge) have larger partition coefficients than rabbit cells in phase systems with or without DEAE-dextran, we have found that a number of other generalities that apply to phase systems containing dextran and polyethylene glycol are reversed by the presence of DEAE-dextran. Thus, an increase in the salt ratio of NaCl/phosphate in a given phase system does not diminish the partition coefficients but instead increases them. The substitution of K + salts by Na + salts by Li + salts in the phase systems also no longer leads to an increase in the partition coefficients but rather to a diminution.

Counter-current distribution of red blood cells of different ages and from different species.

Abstract Red blood cells from a number of different species were subjected to counter-current distribution in an aqueous, buffered dextran-polyethylene glycol, two-phase system. A marked correlation between the distribution of these cells and their relative electrophoretic mobilities was observed, leading to the conclusion that surface charge is a primary determinant in the behavior of cells on counter-current distribution. By injecting some of the animals with 59 Fe we were able to differentiate between young and old red cells in a given cell population. Counter-current distribution permits the separation of young and old cells not only from the rat (as we previously reported) but also from the dog, mouse and even chicken, leading to the conclusion that this is a general phenomenon. Sialic acid has been implicated as bearing almost the total surface charge of red blood cells. Analysis of the stroma from red blood cells of different ages ( i.e. , from cells in the different tubes of the extraction train after counter-current distribution) reveals that the sialic acid content is constant. However, the effective surface charge of red blood cells changes as a function of their age. This is most probably a consequence of the diminution of older red cells' surface 5 , and that their cell membranes become “altered” 14 . It is evidenced by the fact that older red cells can be electrophoretically separated from their younger counterparts 6 . This fact, together with the results obtained on counter-current distribution of red cells from different species, leads us to believe that a difference in surface charge is the primary determinant in the separation by counter-current distribution of red blood cells of different ages. An experiment demonstrating the effect of a different salt composition of the phase system used on the counter-current distribution of labeled red blood cells is also presented.