Red Blood Cell Life Research Articles

The effect of fetal hemoglobin on the survival characteristics of sickle cells

AbstractThe determinants of sickle red blood cell (RBC) life span have not been well-defined but may include both intrinsic factors (eg, the tendency to sickle) and extrinsic factors (eg, the capacity of the reticuloendothelial system to remove defective RBCs). Fetal hemoglobin (HbF) is heterogeneously distributed among sickle RBCs; F cells contain 20% to 25% HbF, whereas the remainder have no detectable HbF (non-F cells). Autologous sickle RBCs were labeled with biotin and reinfused to determine overall survival, non–F- and F-cell survival, and time-dependent changes in HbF content (%HbF) for the surviving F cells. A total of 10 patients were enrolled, including 2 who were studied before and after the percentage of F cells was increased by treatment with hydroxyurea. As expected, F cells survived longer in all subjects. Non–F-cell survival correlated inversely with the percentage of F cells, with the time for 30% cell survival ranging from 6 days in patients with more than 88% F cells to 16 days in patients with less than 16% F cells. As the biotin-labeled RBCs aged in the circulation, the HbF content of the surviving F-cell population increased by 0.28%/d ± 0.21%/d, indicating that within the F-cell population those with higher HbF content survived longer.

Infusion of Autologous Retrodifferentiated Stem Cells into Patients with Beta-Thalassemia

Beta-thalassemia is a genetic, red blood cell disorder affecting the beta-globin chain of the adult hemoglobin gene. This results in excess accumulation of unpaired alpha-chain gene products leading to reduced red blood cell life span and the development of severe anemia. Current treatment of this disease involves regular blood transfusion and adjunct chelation therapy to lower blood transfusion–induced iron overload. Fetal hemoglobin switching agents have been proposed to treat genetic blood disorders, such as sickle cell anemia and beta-thalassemia, in an effort to compensate for the dysfunctional form of the beta-globin chain in adult hemoglobin. The rationale behind this approach is to pair the excess normal alpha-globin chain with the alternative fetal gamma-chain to promote red blood cell survival and ameliorate the anemia. Reprogramming of differentiation in intact, mature, adult white blood cells in response to inclusion of monoclonal antibody CR3/43 has been described. This form of retrograde development has been termed “retrodifferentiation”, with the ability to re-express a variety of stem cell markers in a heterogeneous population of white blood cells. This form of reprogramming, or reontogeny, to a more pluripotent stem cell state ought to recapitulate early hematopoiesis and facilitate expression of a fetal and/or adult program of hemoglobin synthesis or regeneration on infusion and subsequent redifferentiation. Herein, the outcome of infusion of autologous retrodifferentiated stem cells (RSC) into 21 patients with beta-thalassemia is described. Over 6 months, Infusion of 3-h autologous RSC subjected to hematopoietic-conducive conditions into patients with beta-thalassemia reduced mean blood transfusion requirement, increased mean fetal hemoglobin synthesis, and significantly lowered mean serum ferritin. This was always accompanied by an increase in mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) in such patients. No adverse side effects in response to the infusion of autologous RSC were noted.This novel clinical procedure may profoundly modify the devastating course of many genetic disorders in an autologous setting, thus paving the way to harnessing pluripotency from differentiated cells to regenerate transiently an otherwise genetically degenerate tissue such as thalassemic blood.

Hemoglobin A1c levels in non-diabetic patients with end-stage renal disease (ESRD) receiving hemodialysis

Hemoglobin A1c (HbA1c) level represents an established tool to monitor glycemic control in diabetic patients, but the previous commonly used tests of HbA1c in patients with end-stage renal disease (ESRD) may not be reliable because of the presence of anemia, assay interference from uremia, and decreased red blood cell (RBC) life span. HbA1c level measured by turbidimetric immunoassay method is not affected by the above factors. We enrolled 40 non-diabetic ESRD patients receiving hemodialysis and 55 non-diabetic patients without ESRD for this study. HbA1c was analyzed by turbidimetric immunoassays with Synchron CX system. We found that the average HbA1c level in non-diabetic ESRD patients receiving hemodialysis was 5.99% and in the control group was 5.45% (p<0.05). There was no significant difference in fasting glucose levels and Hct % between the two groups (p>0.05). Our limited data indicate that HbA1c levels are elevated in nondiabetic ESRD patients receiving hemodialysis. We propose that the elevated HbA1c level may be due to the repetitive exposure of patients' RBCs to the high glucose level in dialysate (200 mg/dl) or may reflect true glucose intolerance in non-diabetic patients with ESRD.

Membrane lipids and protein-bound carbohydrates status during the maturation of reticulocytes to erythrocytes in type 2 diabetics

Background: The reticulocyte maturation process is an ideal model for the study of biochemical alterations seen during final stage of erythropoiesis under disease conditions. In this study, determined whether type 2 diabetes has any effect on membrane lipids and protein-bound carbohydrates during the maturation of reticulocytes to erythrocytes. Subjects and methods: Lipids (cholesterol and phospholipids) and protein-bound carbohydrates (hexose, hexosamine and sialic acid) were extracted and estimated in plasma, membrane of reticulocytes and erythrocytes from 20 treated but uncontrolled type 2 diabetic volunteers and age matched controls. Results: Plasma, membranes of reticulocytes and erythrocytes of diabetics showed increase in cholesterol (35.7%, 8.7% and 16.4%); phospholipids (43.4%, 18.8% and 8.2%); hexose (34.1%, 19.3% and 8.2%) and decrease in hexosamine (11.9%, 7.3% and 14.7%); and sialic acid (34.1%, 19.3% and 32.0%) compared to controls. As reticulocytes matured to erythrocytes, cholesterol, phospholipids, hexosamine and sialic acid levels were decreased; C/P ratio and hexose levels were increased in both controls and diabetics. However, these alterations were more intensified in diabetics. Conclusion: These alterations in diabetic patients may indicate the existence of one or both of the following conditions: acceleration of maturation processes and/or decreased red blood cell life span.

Simplification of the end-alveolar carbon monoxide technique to assess erythrocyte survival

We have described a simple, rapid method for determining red blood cell (RBC) life span based on measurement of alveolar carbon monoxide (CO) concentration corrected for atmospheric CO as determined with a device that simulates the body’s equilibration with CO. This study was designed to determine whether direct measurements of ambient CO can be substituted for sampling with the equilibrator device. Atmospheric samplings obtained in our medical center over a period of weeks indicated that CO concentration was sufficiently constant that a single ambient CO measurement at the time of breath collection adequately corrected for atmospheric CO. Additional studies with volunteers showed that overnight CO concentrations in the subjects’ home environments also remained relatively constant, suggesting that accurate assessment of RBC life span can be obtained from alveolar CO concentrations and home atmospheric samples collected on a subject’s arising in the morning. Using this technique, we found that the RBC life span of 40 healthy volunteers averaged 122 ± 23 days, a value comparable to that obtained with complex cohort labeling methods. No significant correlation was observed between RBC life span and reticulocyte count in these individuals. The ability of this simple technique to detect increased RBC turnover was demonstrated in 4 subjects being treated with ribavirin and interferon for hepatitis C, a treatment reported to shorten RBC life span. Measurement of CO in samples collected by these four subjects in their home environments indicated that each had a shortened RBC life span (range 30–69 days).

Study on autologous blood transfusion in hemodialysis patients

The storage period of autologous blood of hemodialysis (HD) patients was investigated with focus on the red blood cell life span. Healthy subjects, HD patients administered recombinant human erythropoietin (rHuEPO) preparation at 4,500 units/week and at 9,000 units/week were classified into 3 groups, respectively. Blood cell system and biochemical parameters were investigated at the time of collection (week 0), and weeks 1, 2 and 3 (after 21 days) in the storage. There was no significant difference in serum potassium and total bilirubin between the groups. Compared with the status in week 0, erythrocyte creatine significantly increased in weeks 2 and 3 in the normal group and EPO 4,500 group. And a significant increase in this parameter was noted in the weeks 1 and 2 in the EPO 9,000 group. Furthermore, the value demonstrated by the EPO 4,500 group was significantly higher than that in the normal group at each time point. Compared with the normal group, the value was significantly higher in week 1 in the EPO 9,000 group. However, there was no significant difference between the EPO 4,500 and EPO 9,000 groups. Concerning the transfusion of autologous blood in HD patients, the degree of hemolysis was smaller than that in the normal group. However, in view of the life span of erythrocyte creatine obtained, the duration that is shorter than that in the normal group in the first place is expected to be further curtailed during the storage period. It is assumed that the generally accepted storage period of 21-35 days in the case of autologous blood is not applicable in the case of HD patients.

Antibody screening in 37°C saline. Is it safe to omit it using the indirect antiglobulin (gel) test?

Abstract Pretransfusion tests must detect antibodies that can shorten the life of red blood cells (RBCs). Some studies have demonstrated the existence of clinically significant antibodies detected at 37°C in saline that are not detected by the indirect antiglobulin test (IAT) when the conventional tube test is used. Our aim was to determine whether these antibodies, detected with a 37°C saline tube test, are also detected when a sensitive column gel agglutination method is used. The 2373 pretransfusion samples were tested as they were received (from May 1998 to December 1999), in 37°C saline and by IAT using the DiaMed gel system. The screening tests were performed using 50 μL of 0.8% low-ionic-strength saline suspended RBCs and 50 μL of plasma. The tests were examined for agglutination and hemolysis. Two hundred and thirty three samples (9.81%) were reactive by IAT and 88 (3.70%) by 37°C saline. All 88 samples reactive by 37°C saline also reacted by IAT. These data indicate that 37°C saline is not an essential pretransfusion procedure when the DiaMed gel test is used. Immunohematology 2002;18:13–15.

Effects of ageing and increased haemolysis on the levels of dolichol in rat spleen

Dolichol is a long-chain polyisoprenoid. No enzyme pathway for dolichol degradation was discovered. Dolichol accumulates in human and rodent tissues during ageing. Red blood cells contain a larger amount of dolichol and red blood cell life span is shorter in older rats. The effects of age and of the load of dolichol from red blood cell degradation on the ageing-associated accumulation of dolichol in spleen were studied in 2, 6, 12, 18 and 24 month-old male Sprague Dawley rats fed ad libitum (AL) or on an anti-ageing dietary regimen (EOD). Tissue dolichol was extracted and assayed by HPLC [J. Gerontol. 53A (1998) B87]. Levels of dolichol increased in spleen, liver, kidney and muscle in parallel fashion from the age of 2 to 12 months. Unexpectedly, spleen dolichol decreased in older rats whereas liver, kidney and muscle dolichol increased significantly. The effects of haemolysis on spleen dolichol were tested by the administration of phenylhydrazine. Results show that haemolysis does not increase, but rather decreases the levels of dolichol in erythroclastic organs. It is concluded that the levels of spleen dolichol may decrease in the absence of any known enzymatic degradative pathway if the spleen and its resident phagocytes are forced to cope with a higher number of red blood cells to be cleared. Free-radical mediated decomposition of dolichol by phagocytic cells during erythrophagocytosis might be involved in the process.

Red blood cell life span in the ovine fetus.

Red cell life span within the fetal circulation has not been reported, although erythrocyte life span has been studied in the adult and newborn. The present study quantified red cell life span in 12 chronically catheterized fetal sheep at 97-136 days gestation (term = 150 days) with the use of autologous red cells labeled with [(14)C]cyanate. Cyanate forms a permanent covalent bond with hemoglobin and acts as a permanent red cell label. In the fetuses, blood (14)C activity decreased in a curvilinear fashion with time and reached 50% of the initial activity at 16.4 +/- 1.6 (SE) days. In contrast, (14)C activity of autologous red cells in two adult ewes decreased linearly with time as expected, reached 50% of the initial (14)C activity in 59 days, and yielded life spans of 117 and 121 days. Computer modeling and parameter optimization taking into account growth and skewed life span distribution were used to analyze the (14)C disappearance curve in each fetus. The mean life span of all red cells in the fetal circulation was 63.6 +/- 5.8 days. Mean red cell life span increased linearly from 35 to 107 days as fetal age increased from 97 to 136 days (r = 0.83, P < 0.001). Life span of cells produced at the time of labeling was significantly greater than the mean life span. Fetal growth rate estimated from parameter optimization was 3.28 +/- 0.72%/day; this compared well with the rate of 3.40 +/- 0.14%/day calculated from fetal weights at autopsy. Mean corpuscular volume decreased as a function of gestational age, but the decrease was small compared with the large increase in red cell life span. We conclude the following: 1) red cell life span in the fetal circulation is short compared with the adult; 2) red cells in younger fetuses have shorter life spans than in near-term fetuses; 3) the curvilinear disappearance of labeled red cells in the fetus appears to be due primarily to an expanding blood volume with fetal growth; and 4) red blood cell life span in a growing organism will be significantly underestimated unless the expansion of blood volume with growth is taken into account.

Kinetics of carbamylated haemoglobin in acute renal failure.

Carbamylation of proteins by isocyanic acid, the reactive form of cyanate derived from urea, is increased in uraemia and may contribute to uraemic toxicity. Kinetics of carbamylation that may reflect uraemic toxicity is not clearly defined in acute renal failure (ARF). Twenty-eight patients with ARF and 13 with chronic renal failure (CRF) were included in the study in order to determine changes in carbamylated haemoglobin concentration (CarHb) in ARF. The usefulness of this parameter for differentiating ARF from CRF was also investigated. CarHb was measured by high-performance liquid chromatography after acid hydrolysis. Mean CarHb level (expressed as microg carbamyl valine per gram (CV/g) Hb) was significantly higher in ARF (54.3+/-5.2) than in normal subjects (31.6+/-1.3). On admission, CarHb level was correlated with duration of ARF prior to hospitalization in the intensive care unit (r(2)=0.723, P<0.001). CarHb was significantly higher at recovery in the subgroup of patients requiring haemodialysis than in the subgroup not requiring haemodialysis (82. 4+/-11.3 vs 46.7+/-5.2, P<0.01). Similarly dialysis patients lost more weight (8.6+/-1.4 vs 2.7+/-0.5 kg, P<0.005) and had higher averaged blood urea levels in the 20 days prior to recovery (17. 6+/-1.9 vs 11.3+/-1.8 mol/l, P<0.05). After recovery, CarHb level decreased at a rate of 0.219 microg CV/g Hb per day in patients with reversible renal insufficiency. CarHb concentration was higher in patients with CRF. A cut-off CarHb value of 100 microg CV/g Hb had a sensitivity of 94% and a positive predictive value of 94% for differentiating ARF from CRF. Kinetics of CarHb showed a near normal red blood cell life span in ARF. Changes in CarHb enabled, with a good sensitivity, the distinction to be made between patients who recovered from ARF and those with sustained renal impairment, whether due to prior CRF or resulting from parenchymal sequelae. Measurement of CarHb is valuable at clinical presentation of ARF in patients with an unknown medical history of renal disease.

Increased Sensitivity to Complement and a Decreased Red Blood Cell Life Span in Mice Mosaic for a Nonfunctional Piga Gene

The gene PIGA encodes one of the protein subunits of the 1-6-N acetylglucosaminyltransferase complex, which catalyses an early step in the biosynthesis of glycosyl phosphatidylinositol (GPI) anchors. PIGA is somatically mutated in blood cells from patients with paroxysmal nocturnal hemoglobinuria (PNH), leading to deficiency of GPI-linked proteins on the cell surface. To investigate in detail how inactivating mutations of the PIGA gene affect hematopoiesis, we generated a mouse line, in whichloxP-mediated excision of part of exon 2 occurs on the expression of Cre. After crossbreeding with EIIa-cre transgenic mice, recombination occurs early in embryonic life. Mice that are mosaics for the recombined Piga gene are viable and lack GPI-linked proteins on a proportion of circulating blood cells. This resembles the coexistence of normal cells and PNH cells in patients with an established PNH clone. PIGA(−) blood cells in mosaic mice have biologic features characteristic of those classically seen in patients with PNH, including an increased sensitivity toward complement mediated lysis and a decreased life span in circulation. However, during the 12-month follow-up, the PIGA(−) cell population did not increase, clearly showing that a Piga gene mutation is not sufficient to cause the human disease, PNH.

Increased Sensitivity to Complement and a Decreased Red Blood Cell Life Span in Mice Mosaic for a Nonfunctional Piga Gene

AbstractThe gene PIGA encodes one of the protein subunits of the ∝1-6-N acetylglucosaminyltransferase complex, which catalyses an early step in the biosynthesis of glycosyl phosphatidylinositol (GPI) anchors. PIGA is somatically mutated in blood cells from patients with paroxysmal nocturnal hemoglobinuria (PNH), leading to deficiency of GPI-linked proteins on the cell surface. To investigate in detail how inactivating mutations of the PIGA gene affect hematopoiesis, we generated a mouse line, in whichloxP-mediated excision of part of exon 2 occurs on the expression of Cre. After crossbreeding with EIIa-cre transgenic mice, recombination occurs early in embryonic life. Mice that are mosaics for the recombined Piga gene are viable and lack GPI-linked proteins on a proportion of circulating blood cells. This resembles the coexistence of normal cells and PNH cells in patients with an established PNH clone. PIGA(−) blood cells in mosaic mice have biologic features characteristic of those classically seen in patients with PNH, including an increased sensitivity toward complement mediated lysis and a decreased life span in circulation. However, during the 12-month follow-up, the PIGA(−) cell population did not increase, clearly showing that a Piga gene mutation is not sufficient to cause the human disease, PNH.

Evaluation of Biochemical Changes During In Vivo Erythrocyte Senescence in the Dog

AbstractOne hypothesis to explain the age-dependent clearance of red blood cells (RBCs) from circulation proposes that denatured/oxidized hemoglobin (hemichromes) arising late during an RBC's life span induces clustering of the integral membrane protein, band 3. In turn, band 3 clustering generates an epitope on the senescent cell surface leading to autologous IgG binding and consequent phagocytosis. Because dog RBCs have survival characteristics that closely resemble those of human RBCs (ie, low random RBC loss, ≈115-day life span), we decided to test several aspects of the above hypothesis in the canine model, where in vivo aged cells of defined age could be evaluated for biochemical changes. For this purpose, dog RBCs were biotinylated in vivo and retrieved for biochemical analysis at various later dates using avidin-coated magnetic beads. Consistent with the above hypothesis, senescent dog RBCs were found to contain measurably elevated membrane-bound (denatured) globin and a sevenfold enhancement of surface-associated autologous IgG. Interestingly, dog RBCs that were allowed to senesce for 115 days in vivo also suffered from compromised intracellular reducing power, containing only 30% of the reduced glutathione found in unfractionated cells. Although the small quantity of cells of age ≥110 days did not allow direct quantitation of band 3 clustering, it was nevertheless possible to exploit single-cell microdeformation methods to evaluate the fraction of band 3 molecules that had lost their normal skeletal linkages and were free to cluster in response to hemichrome binding. Importantly, band 3 in RBCs ≥112 days old was found to be 25% less restrained by skeletal interactions than band 3 in control cells, indicating that the normal linkages between band 3 and the membrane skeleton had been substantially disrupted. Interestingly, the protein 4.1a/protein 4.1b ratio, commonly assumed to reflect RBC age, was found to be maximal in RBCs isolated only 58 days after labeling, implying that while this marker is useful for identifying very young populations of RBCs, it is not a very sensitive marker for canine senescent RBCs. Taken together, these data argue that several of the readily testable elements of the above hypothesis implicating band 3 in human RBC senescence can be validated in an appropriate canine model.

Autoimmune hemolytic anemia.

Immune hemolytic anemia can be either isoimmune or autoimmune. Autoimmune hemolytic anemias (AIHA) consist of group of disorders whose common characteristics are the presence of an antibody which in turn causes short red blood cell (RBC) life. The rate and site of hemolysis and hence the clinical manifestations depends on the type of antibody attached and its propensity to fix complement. Antibodies of the IgG class are most commonly responsible for AIHA in children. Rh erythrocyte antigen is involved in more than 70% of cases. Since the antibody has its maximal activity at 37 degrees C, the resultant hemolysis is called warm antibody induced hemolytic anemia. This is a severe life threatening condition, the clinical features are: sudden onset of pallor, jaundice and dark urine. The cornerstone of diagnosis is a positive Coomb's antiglobulin test in the presence of hemolysis. Coomb's test has false negative and false positive rates in about 2-4% and 8% of all cases respectively. The modalities for treatment of warm AIHA include blood transfusion, steroid therapy, intravenous gammaglobulin, plasma-pheresis and splenectomy. The choice depends on the severity of the disease and child's response to therapy.

The life span of erythrocytes transfused to preterm infants.

This study was made to determine the life span of adult red cells transfused to early preterm infants. Nineteen very preterm infants (birth weight, 878.7 +/- 221 g; gestational age, 26.8 +/- 1.5 wk at birth) were sampled weekly after their last blood transfusion to determine the level (%) of fetal Hb in their circulation. Two microliters of blood were subjected to reverse phase HPLC to separate the alpha, beta, and gamma globin components of their Hbs. The percent of fetal Hb (HbF) was calculated as gamma/gamma + beta x 100. The life span of the adult erythrocytes transfused was defined as the time interval between the transfusion and when the percentage of HbF in the recipient's circulation returns to the HbF levels that exist in the infant's autologous red cells (the maximum post transfusion HbF level). Twelve of the 19 infants were followed until their autologous HbF levels were reached. Their mean adult red blood cell life span was 56.4 +/- 7 d (range: 46-68 d). The results obtained in this study imply that the number of days after a transfusion at which half the cells infused remain in the circulation in a preterm infant is about 30 d.

Recent developments in the long-term preservation of red blood cells.

The first study to suggest the successful prolongation of the useful shelf life of red blood cells (RBCs) used a hypotonic additive solution containing glycerol. It was necessary to use twice the volume of this solution than the commercial additive solution per unit of packed RBCs. The final concentration of glycerol in the units was approximately 0.69% (75 mmol/L). A subsequent study demonstrated that the membranes of the exocytic microvesicles shed during storage had less of bands 3 and 4.1 than those in Adsol (Fenwal Laboratories, Deerfield, IL). Band 4.1 is important for strengthening the bonds between spectrin and actin in the cytoskeleton. In another study, glutamine or glutamine plus phosphate was used in a hypotonic additive solution, otherwise similar to the glycerol-containing additive. In the latter medium, phosphatidylethanolamine was less accessible to phospholipase action than in Adsol or when glutamine alone was added. Another group reported encouraging data regarding the action of L-carnitine when added to AS-3. Acylation of phosphatidylethanolamine mediated by the action of carnitine fatty acid transferase with acyl coenzyme A (acyl-CoA) occurred. Adenosine-5'-triphosphate levels and red cell recovery were better in the test units. In the last paper reviewed, the authors demonstrated that oxidant damage of erythrocytes was less if the donors were given a mixture of antioxidants for 10 days prior to donating.

Comparison between radioactive isotope chromium-51 and stable isotope chromium-50 labels for the determination of red blood cell survival

Radioactive 51Cr labelling is the most common method for the determination of red blood cell (RBC) life spans. The use of alternative non-radioactive or stable isotopes also provides a means of labelling. The purpose of the present work was to determine whether labelling with non-radioactive 50Cr could provide an alternative to radioisotope labelling with 51Cr for the determination of RBC life spans. The survival of RBCs labelled with both non-radioactive 50Cr and radioactive 51Cr was monitored by measuring the half-lives (t½) using inductively coupled argon plasma mass spectrometry (ICP-MS) for 50Cr and using a gamma counter for 51Cr. The values determined were statistically similar at the 95% probability level.

Total body haematocrit iron kinetics and erythrocyte life span in pigeons ( Columba livia)

1. 1. The mean pigeon erythrocyte life span was found to be 17–25 days by Cr 51-labeled erythrocytes and 21 ± 3.4 days by iron kinetics. 2. 2. Total red blood cell volume has been calculated by Cr 51-labeled erythrocytes while total plasma volume was determined both by a dye method and iron kinetic data. From these results total blood volume and total body haematocrit were found to be 0.090 ± 0.002 ml/g body wt and 36 ± 4.3%, respectively. 3. 3. Venous haematocrit, haemoglobin concentration, erythrocyte count, mean corpuscular haemoglobin concentration, plasma iron and red blood cell iron have also been measured. 4. 4. A significant difference between total body and venous haematocrit and a short mean red blood cell life span, due to ageing and to random destruction of erythrocytes were shown. 5. 5. The above observations are compared with analogous available data for human beings and their physiological significance is discussed.

Hemolysis in sickle cell disease as measured by endogenous carbon monoxide production. A preliminary report.

To detect and quantitate temporal variations of the hemolytic rate in sickle cell disease, the authors measured endogenous carbon monoxide (CO) production in five normal subjects, nine patients with sickle cell anemia (SS) in steady clinical state, and two patients with sickle cell-hemoglobin C (SC) disease in and out of pain crises. The red blood cell life span calculated from these data (RCLSco) ranged from 81.2 to 102.9 days (mean +/- standard deviation [SD] 88.0 +/- 9.2, coefficient of variation [CV] 10.2%) for the normal subjects and 8.0-24.7 days (mean +/- SD 12.1 +/- 5.1, CV 42.1%) for those with SS. Although the individual figures for RCLSco for the normal subjects and those with SS fell within the range previously obtained by radioisotopic techniques for the respective groups, the mean values calculated from the CO technique were slightly (though not significantly) shorter for the normal subjects and about 25% shorter for the subjects with SS (P less than 0.01). Repetitive studies were performed in four subjects with SS who were clinically stable; the temporal variability in the calculated hemolytic rate differed considerably from patient to patient (CV 3.6%, 7.0%, 17.0%, 28.0%). In two patients concurrent RCLS studies were performed by the CO technique and 51Cr tagged red blood cells. In one patient, the RCLS was similar by the two techniques, in the other, a two exponent 51Cr curve did not permit calculation of RCLS. In the two patients with SC disease there was no difference in RCLSco during and after recovery from pain crisis. Although the CO technique may overestimate the turnover of circulating heme mass, especially in the presence of hemolysis, the results of serial studies in a small number of patients with SS suggest but do not prove temporal variations in hemolytic rate in SS.

The effect of adenine on platelet storage.

Adenine is an approved additive to citrate-phosphate-dextrose anticoagulant for whole blood collection and extends the storage life of red blood cells. We used in vitro methods to investigate the effects of adenine on platelet function and viability during 72 hours of storage at 22 degrees C. Although the hypotonic shock response and aggregation were decreased, these effects were reversed following separation and resuspension in fresh adenine-free plasma. Serotonin uptake and release were not affected by adenine, however malonaldehyde formation was slightly enhanced. Glucose, pH and pO2 levels were lower, while lactate levels were slightly higher than in platelets stored without adenine. These results indicate little in vitro effect of adenine on platelets stored as platelet-rich plasma or platelet concentrate.