Alterations in Vascular Endothelial Cell-related Plasma Proteins In Thalassaemic Patients and their Correlation with Clinical Symptoms

An increased level of plasma thrombomodulin (TM) in α- and β- thalassaemia was demonstrated using an enzyme-linked immunosorbent assay (ELISA). Nonsplenectomized patients with β-thalassaemia/ haemoglobin E (BE) had higher levels of TM than splenectomized cases (BE-S). Patients with leg ulcers (BE-LU) were found to have the highest increase in TM level. Appearance of larger platelets in all types of thalassaemic blood was observed indicating an increase in the number of younger platelets. These data indicate that injury of vascular endothelial cells is present in thalassaemic patients.

International Council for Standardization in Haematology (ICSH) recommendations for "surrogate reference" method for the packed cell volume

The spun packed cell volume (PCV, hematocrit) is a key measurement on which are based hematology instrument calibration, reference range determination, and assignment of values to calibrators/controls. In 2001, the International Council for Standardization in Haematology (ICSH) recommended a Reference PCV method, which is fully traceable to the ICSH reference hemoglobin method. Because of its complexity, however, this method is impractical for occasional use in routine laboratories and is therefore intended primarily for use by manufacturers of capillary microhematocrit tubes, liquid calibrators, and multichannel analyzers. In response to the need for a simpler method--accessible to all routine laboratories--the ICSH offers this "Surrogate Reference" PCV procedure. It is traceable to the original ICSH Reference PCV method and is based on spun PCVs obtained using borosilicate capillary tubes with an already-known relationship to this reference procedure. This ICSH "Surrogate Reference" PCV method is substantially simpler, thus putting it within the reach of most routine hematology laboratories.

Automated detection of morphological alterations during apoptosis

A convenient means of measuring apoptosis is described using an automated analyzer (MF-1; Sysmex), which normally provides rapid measurement of malarial parasites. By means of this MF-1 procedure, apoptotic cells exhibited characteristic changes of light scatter (size) and fluorescence (DNA content) relating to cell shrinkage and nuclear fragmentation of apoptosis.

Plan and process for hematology laboratory standard in Thailand

In Thailand, there are around 2,000 clinical laboratories in private and government hospitals, By the end of year 2004, all of these laboratories are required to use the same or comparable standard nationwide. Many laboratories are in the process of starting ISO/IEC Guide 25 for the fulfillment of laboratory accreditation. To run the standard system of hematology laboratories in Thailand, we have considered three main aspects: standard in process, method selection and academic interpretation. Because of the wide spectrum of blood diseases in Thailand: thalassemia, iron deficiency anemia and G6PD deficiency hemolytic disease, the analysis and interpretation of laboratory results using different technology are of great importance. National plan has thus set up in two direction, one for standard process and another for academic approach.

Field evaluation of who hemoglobin color scale in West Java

The results obtained with a WHO hemoglobin (Hb) colour scale were evaluated in a field study in Chibubur district in Java island by comparison with hemoglobin values obtained by an automated blood cell analyzer K-800 (Sysmex. Kobe, Japan). When the color scale test was performed following the instructions for use. Hb values observed were usually higher than the values obtained by the analyzer. Thirty microl blood was loaded on the filter paper and an 60 sec waiting period was used. The sensitivity of results obtained with the color scale was 23.3% (14/60), and specificity was 96.6% (58/60). We propose an additional testing method based on our results.

Laboratory accreditation: quality in management and analysis and the input-output control

An attempt to overcome the uncertainties and errors of all processes in clinical laboratory has been done in systematic ways. To reach the stage of laboratory accreditation, quality and standard criteria in the laboratory must be developed. Two aspects of quality are considered as management and analysis. Input-output control is proposed to handle the process from the beginning of laboratory design until post analytical phase or the control at the outcome. The model of ten Ms including model, material, machine, man, mind, money, method, mechanism, measurement and menace and one O or outcome, is elaborated to cover pre-analytical, analytical and post-analytical phases. Laboratory accreditation is then an integral part of hospital accreditation with total quality management.

Icsh activities and Asia

The International Council for Standardization in Haematology (ICSH), an international organization promoting international agreement on hematological testing, is now restructuring to strengthen its activities. In Asia, a diversity of testing methods exists and the resulting testing levels make it difficult to compare test results internationally among Asian countries. Fortunately, the ICSH is considering regionalizing its organization to 5 sub-societies to increase its activity, and we have been able to establish a new society, ICSH-Asia, under the ICSH umbrella.

Hematology laboratory standardization: a plan for harmonization in Asia

Hematology laboratory is generally required in the hospital. At the macroscale, hematology laboratories have served a large number of population. In Asia, more than 3,000 million people are potentially to use the hematology laboratory service, particularly the complete blood count. Since 1970s, automated technology has been introduced to Asia and as years passed by, technology diversity is increasing. However, there are considerable number of hematology laboratories that have no automated machine. They are still relied on manual technology which is still variable in spectrophotometer for hemoglobin determination, centrifuge for hematocrit and diluting pipet for cell counting. In particular, blood smear preparation and interpretation are very difficult to control for standardization from person to person and laboratory to laboratory. Different methodology and a large population in the huge geographical area in Asia, the agreement of standard criteria is greatly important. This report has shown strategy and action plan to reach the goal of hematology laboratory standardization in Asia.

A rapid measurement of apoptosis-associated light scatter changes using a hematology analyzer

The alternative application of an automated hematology analyzer, H*3 system, has been described for the detection of apoptosis. Apoptosis induction by the topoisomerase I inhibitor, camptothecin (CAM) on several cell lines is followed by typical morphological alterations. On the H*3 cytogram, measurement of CAM-treated cells revealed an increased population of cells with reduced size suggesting cell contraction during apoptosis. The decreased LUC/Lymph ratio also indicated the enhanced degree of apoptosis directly correlated with increasing CAM concentration and/or incubation period. Quantitative analysis shows a good correlation between the H*3 measurement and flow cytometry measurements of Annexin V-fluorescein isothiocyanate-labeled method. Thus, the H*3 measurement, under an appropriate adjustment, can be used as a rapid monitor for evaluating the degree of apoptotic changes in drug susceptibility testing of homogeneous cell samples.

Reticulocyte analysis in iron deficiency anemia and hemolytic anemia

Reticulocyte analysis was studied in 28 anemic patients, 15 with iron deficiency anemia (IDA), and 13 with hemolytic anemia including 9 glucose 6 phosphate dehydrogenase deficiency (G6PD def.), and 4 with G6PD def. combined with HbE trait or alpha thalassemia trait (alpha thal trait). The reticulocyte analysis among these patients showed the increased number of reticulocyte percentage with low degree of maturation in both IDA and G6PD def. patients. The significantly decreased reticulocyte hemoglobin content (CHr) was found in IDA (CHr = 21.74 +/- 4.61 pg in IDA vs 28.41 +/- 1.34 pg in normal; p-value = < 0.0001), whereas, increased CHr was found in G6PD def. patients. In addition, the G6PD def. patients also showed a significant increase in mean corpuscular reticulocyte volume (MCVr) when compared to normal (MCVr = 132.0 +/- 8.39 fl. in G6PD def. vs 110.39 +/- 5.09 in normal; p-value = < 0.0001). However, a significant decrease in MCVr was found in IDA patients (MCVr = 95.89 +/- 8.57 fl.; p-value = < 0.0001 vs normal). From this study, we can suggest that the reticulocyte hemoglobin content (CHr) and mean corpuscular reticulocyte volume (MCVr) are the important defects in patients with iron deficiency anemia.

Reticulocyte analysis in systemic lupus erythematosus and chronic renal failure using flow cytometry

The number and maturation of circulating reticulocytes were measured in patients with systemic lupus erythematosus (SLE) and chronic renal failure (CRF) using an automated hematological analyzer (Technicon H*3 RTX) for their erythropoietic activities. Both SLE and CRF patients had increased reticulocyte numbers with a low degree of maturation. The SLE patients had no changes in mean reticulocyte corpuscular volume (MCVr) as compared to normal subjects (110.20 +/- 15.43 fl. in SLE and 110.39 +/- 5.09 fl. in normal), whereas CRF patients had significantly increased mean corpuscular reticulocyte volume (MCVr = 120.99 +/- 8.09 fl., p-value = 0.0019 as compared with normal). Three cases of SLE with nephrotic syndrome (NS) had high degree of MCVr (113.4, 125.0 and 133.1 fl., respectively). The renal involvement in SLE patients and CRF patients may associate with increased reticulocyte corpuscular volume.

Indices of iron status in continuous ambulatory peritoneal dialysis patients

Data for iron-status indices in continuous ambulatory peritoneal dialysis patients are limited. The reliability of commonly used indices for the diagnosis of iron-deficiency anemia in peritoneal dialysis patients is still unknown. To study diagnostic values of iron-status indices, including serum ferritin, transferrin saturation, reticulocyte hemoglobin content, and bone marrow-stainable iron, 21 stable anemic peritoneal dialysis patients who have been treated with erythropoietin and oral iron supplementation for more than 3 months were enrolled in this study. The mean age was 51.4 +/- 2.9 years; dialysis duration, 28.7 +/- 5.1 months; initial hemoglobin, 8.4 +/- 0.2 g/dL; erythropoietin dosage, 71 +/- 2 micro/kg/wk; serum albumin, 3.5 +/- 0.1 g/dL; intact parathyroid hormone (PTH), 233 +/- 44 ng/mL; serum ferritin, 643 +/- 135 ng/mL; transferrin saturation, 33.93% +/- 3.9%; and reticulocyte hemoglobin content, 31.6 +/- 4 pg. Bone marrow aspiration was performed in all patients to determine marrow iron content and exclude hematological disorders. All patients were treated with 1, 000 mg of intravenous ferric saccharate infusion in two divided doses more than 1 week apart. Patients who responded to the iron infusion within 3 months by increasing serum hemoglobin of greater than 1 gm/dL more than baseline were defined as being functional iron deficient before the intravenous iron infusion. Serum ferritin, transferrin saturation, and reticulocyte hemoglobin content were followed serially after iron infusion. Fifteen patients (71.4%) responded to the iron administration, indicating iron deficiency. Nine of 13 (69%) patients with the presence of bone marrow-stainable iron still responded to intravenous iron supplementation, suggesting functional iron deficiency. Absence of bone marrow-stainable iron was not a sensitive marker for the diagnosis of iron deficiency, 25% sensitivity. No single value of iron-status indices that can definitely exclude iron-deficiency anemia in peritoneal dialysis patients was found. Therefore, failure to increase hemoglobin concentration after intravenous iron administration should be shown before excluding iron-deficiency anemia as a cause of poor erythropoietic response to erythropoietin therapy.

Serum vitamin A and E in pregnant women with hemoglobinopathies

OBJECTIVE

To evaluate the relationship between the status of serum vitamin A, E and hemoglobinopathies among Thai pregnant women.

METHODS

This was a cross-sectional study in which serum vitamin A and E were assessed in 323 pregnant women with normal hemoglobin and 73 with hemoglobinopathies (47 with hemoglobin E and 26 with thalassemia) during the first trimester.

RESULTS

There were no significant differences in the mean serum vitamin A, E concentrations and vitamin E/cholesterol ratio between pregnant women with normal hemoglobin and hemoglobinopathies, while confounding variables that might affect serum vitamin levels i.e. maternal age, gravida, BMI, gestational age, hematocrit, hemoglobin, mean corpuscular hemoglobin concentration and blood group were not different.

CONCLUSION

The results of this study suggest that antenatal care in terms of micronutrients-vitamin A, E in Thai pregnant women with hemoglobinopathies should not be different from normal pregnant women.

Dengue viruses induce cell proliferation and morphological changes of endothelial cells

Replication of dengue viruses (type 1, 2, 3 and 4) in vitro in endothelial cells from human umbilical cord vein was demonstrated by virus titers and immunofluorescent antibody studies. Both showed highest peak at Day 6 after inoculation and declined to origin at Day 14. Some of the cultured endothelial cells detached from the culture well. Most of these floating cells were rarely viable as shown by failure in trypan blue exclusion whereas the adhering cells are mostly viable. More frequent and higher intensity of immunofluorescent positive cells were found in the detached cells as compared to adhering cells. The virus titers in the supernatant and in the adhering cell population were comparable, although floating cells were maximally 26.2% of the total cultured endothelial cells. Many floating cells and occasional adhering cells had numerous blebs on their surface. Endothelial cell proliferation was markedly increased after virus inoculation as compared with the control. Increased number of mitotic cells was also observed in the dengue virus-endothelial cell culture. Comparing among the four types, dengue type 4 induced highest peaks of cell proliferation and cell mitosis at Day 10 after inoculation. Dengue type 2 had the highest virus titers both in adhering cells and in supernatant at Day 6 as compared with other types.

An in vitro study on thalassemic erythroid precursors in liquid culture

Thalassemia is an inherited hematological disorder which can generally be classified according to the affected globin imbalance (alpha- or beta-globin) into two main types, i.e. alpha-thalassemia and beta-thalassemia, respectively. There is a wide range of cellular abnormalities associated with thalassemic erythrocytes such as hypochromia, microcytosis, reduced cellular deformability and membrane oxidative damage. The red cell abnormalities lead to premature destruction with marrow erythroid hyperplasia and ineffective erythropoiesis. The abnormalities in thalassemic red blood cells have been found along the erythroid differentiation pathway other than the mature stage as previously shown in bone marrow erythroid precursors and in reticulocytes, the penultimate stage of erythroid differentiation. However, there is a lag in our understanding of the more primitive erythroid stages due to the difficult and hazardous marrow aspiration and heterogeneity of cells derived. We have utilized a novel method of Two-Phase Liquid Culture (TPLC) of beta-thalassemia/HbE erythroid precursors instead of conventional semisolid culture. This type of liquid culture can given higher cell yield with quite synchronous cell differentiation stages and easily be applied for other cellular analytical techniques. The peripheral blood mononuclear cells (PBMC) obtained from non-splenectomized and splenectomized beta-thalassemia/HbE patients were first cultured in medium supplemented with 5637 conditioned medium for a 6-day period (phase I) and then transferred to medium supplemented with recombinant human erythropoietin to allow the terminal differentiation of erythroid precursors (phase II). During the phase I or II, the cultured cells were periodically sampled to determine the cell number, cytocentrifuged on glass slides and stained with Wright stain for morphological assessment of their differentiation stages and analyzed flow cytometrically by staining with fluoresceinated anti-transferrin receptor (anti-CD71) and R-phycoerythrin-conjugated anti-glycophorin A. After assessment by flow cytometry, the remaining stained cells were cytocentrifuged on glass slides and photographed by a fluorescent microscope and a laser scanning confocal microscope. The results of morphological assessment, flow cytometric analysis and microscopic pictures will be presented.

Detection of thalassemia genes using smeared blood film or leukocytes adhering to polysthylene fibers

Presently genetic analyses for thalassemia types require relatively large amounts of heparinized blood (5 to 10 ml), and transport as well as degeneration of these sample is a problem in the developing world. We have developed a new method to simplify this procedure and obtain DNAs from small specimens. As experimental materials, thinly smeared blood on a glass slide or blood filtered with and adhered on polysthylene telephtalate (PST) fibers were used. These materials could be safely stored without interfering with DNA extraction for up to 3 months. The slide materials were digested with proteinase K, and DNA was extracted with Tris-EDTA-phenol:chloroform and precipitated with absolute ethanol. The PST specimens were washed with physiologic saline and treated in the same manner as described above. Products were easily amplified by PCR and digested with restriction endonucleases for beta thalassemia typing as well as for HLA-DQA1 gene typing. Results obtained by this method correlated well with previously reported incidences for thalassemia and HLA-DQA1 types in Thailand. This method can be used in the routine laboratory because it allows for stable and biosafe genetic analyses.

Morphological alterations and apoptosis of endothelial cells induced by thalassemic serum in vitro

Vascular complications such as lung thromboembolism and leg ulcer have been observed in thalassemic patients. Recently, our group has reported impaired proliferation of endothelial cells (ECs) after exposure to alpha- and beta-thalassemic sera in a culture system. This study was undertaken to detect apoptotic phenomena of ECs in the presence of alpha- and beta-thalassemic serum. ECs from normal human umbilical cord vein were exposed to 30% thalassemic serum in vitro and morphological changes were observed by using phase contrast, fluorescence and scanning electron microscopy. Such treated ECs presented morphological characteristics of apoptosis as shown by the appearance of compact cytosol, membrane blebbing, margination of nuclear matrix, condensed nuclei, and fragmented bodies. The majority of apoptotic cells was in the floating population. Similar morphological changes were also observed by treating ECs with hydrogen peroxide in the concentration range of 0.1-10 mM.

Malaria protection in hereditary ovalocytosis: relation to red cell deformability, red cell parameters and degree of ovalocytosis

In the culture of red cells with Plasmodium falciparum, erythrocytes from both Thai patients and subjects (patient's parents) with hereditary ovalocytosis have a protective effect against malarial infection. High percentage of ovalocyte (75-100%) was found in patients whereas their parents had lower percentage (25-50%). Invasion index (II) and multiplication ratio (MR) of P. falciparum in these abnormal red cells from the patients were significantly decreased as compared to those in normal red cells (patients: II = 1.52 +/- 0.91, MR = 8.83 +/- 6.73; normal subjects: II = 4.45 +/- 1.51, MR = 25.23 +/- 6.25). This suggests that the red cells from these patients had significant degree of malaria protection. The significant protection was also shown in red cells from the parent group (II = 1.86 +/- 0.81, MR = 15.69 +/- 3.50). Although the parents had lower ovalocyte percentage, degree of protection against malaria parasite was as effective as those found in patients with high ovalocytic red cells. This has been confirmed by statistical analysis showing nonsignificant difference in II value between the two groups. In contrast, red cells of both groups had poor deformability (deformability index, DI) as compared to the normal group. No statistically different DI values were demonstrated between the two. This indicates that poorly deformable red cells, not their ovalocytic shape, make a significant contribution to limitation of malaria parasite invasion. The MR values in patients were less than those found in the parent group but statistical analysis showed no significant difference. Reduced MR values were found with increased numbers of microcytic, hyperchromic and hypochromic red cells in patients.

Thalassemic serum inhibits endothelial cell mitosis in vitro

Human umbilical vein endothelial cells were cultured in vitro using Iscove's Modified Dulbecco's Medium (IMDM) supplemented with either pooled normal human serum, or pooled thalassemic serum, or autologous umbilical cord serum, or fetal bovine serum. The mitotic activity was determined under the inverted phase contrast microscope and the number of mitotic cells was counted. Our results showed that the mitotic cells decreased in endothelial cell culture with thalassemic serum as compared with normal human serum, autologous umbilical cord serum or fetal bovine serum. The percentage of mitotic cells decreased on day 3 in the presence of beta-thalassemia/HbE serum from both splenectomized and non-splenectomized patients as compared with normal or autologous umbilical cord serum. In the presence of alpha-thalassemic serum, a similar outcome was also observed. From this study we can conclude that the thalassemic sera might contain factors which affect the endothelial cell growth and proliferation by inhibiting mitosis in vitro.

Red cell parameters in alpha-thalassemia with and without beta-thalassemia trait or hemoglobin E trait

Eighty-five patients who attended at Ramathibodi Hospital during November 1994 to June 1996 were investigated for thalassemia genotype, hemoglobin (Hb) typing and blood cell parameters. All patients were screened primarily for complete blood count using the Technicon H*3 automated hematology analyzer and Hb typing using the automated HPLC. Their genotypes were evaluated by in vitro gene amplification using primers for detection of common alpha-thalassemic genes found in the Thai population. We found 45 cases out of 85 were alpha-thalassemia trait with A2A typing, 10 were normal, 7 were alpha-thalassemia trait complicated by beta-thalassemia trait or HbE trait, 18 were HbH disease or HbH with Hb Constant Spring (HbH/CS), and 5 were AE Bart's disease. The alpha-thalassemia 1 trait had heterogeneity in red cell population as shown by increased red cell distribution width (RDW), the increased percent microcytic red cell (%Micro) and decreased mean cell volume (MCV). Red cell parameters in alpha-thalassemia 2 trait and HbCS trait were not significantly different from normal. The cases with coinheritance of alpha-thalassemia trait with beta-thalassemia trait or with HbE trait showed variation in their red cell parameters: one case showed less abnormal red cell parameters than those of uncomplicated alpha-thalassemia but the other two cases showed unimproved values. The homozygous alpha-thalassemia 2 showed similar red cell parameters to the alpha-thalassemia 1 trait. In conclusion, we can screen the alpha-thalassemia 1 trait and homozygous alpha-thalassemia 2 by using the simple red cell parameters such as the MCV and RDW; however, they must be confirmed for alpha-thalassemic genes. Unfortunately, red cell parameters of alpha-thalassemia 2 trait or HbCS trait were not different from those of normal subjects.

Possible evidence of endothelial cell activation and disturbance in thalassemia: an in vitro study

Activation of vascular endothelium is considered as an important facet of inflammation, thrombosis, and vasculitis. Activated endothelial cells express a number of immunologically relevant surface markers which are not detected in dormant condition. These surface markers on endothelial cell may involve in adhesion reaction and migration of blood cell components. We demonstrated increased level of the soluble adhesion molecules in circulating blood of both alpha- and beta-thalassemic patients. These adhesion molecules are theoretically known to be released from endothelial cells. The adhesion molecules included soluble Intercellular Adhesion Molecule-1 (sICAM-1), soluble E-Selectin (ELAM-1), soluble Vascular Cell Adhesion Molecule-1 (sVCAM-1), and von Willebrand Factor (vWF). The levels of these adhesion molecules were measured in serum from 32 thalassemic patients and 10 control healthy subjects. As compared to normal, increased sICAM-1 was found in beta-thal/HbE patients with non-splenectomy; BE-NS (p = 0.002), increased ELAM-1 in beta-thal/HbE patients with splenectomy; BE-S (p = 0.01) and HbH with Hb Constant Spring; HbH/CS (p = 0.001), and increased sVCAM-1 in BE-NS; (p = < 0.0001) and BE-S (p = 0.002). Significant increase in von Willebrand Factor (vWF), a marker for endothelial cell, was shown in BE-S (p = 0.04) as compared to normal. Adhesion molecules were also markedly demonstrated in the supernatant of in vitro culture of human vascular endothelial cell in the presence of 30% thalassemic serum, and these adhesion molecules were also detected on the surface of the cells by using the technic of laser scanning confocal microscope and direct immunofluorescence.

Membrane phospholipid asymmetry in human thalassemia

Phospholipid asymmetry in the red blood cell (RBC) lipid bilayer is well maintained during the life of the cell, with phosphatidylserine (PS) virtually exclusively located in the inner monolayer. Loss of phospholipid asymmetry, and consequently exposure of PS, is thought to play an important role in red cell pathology. The anemia in the human thalassemias is caused by a combination of ineffective erythropoiesis (intramedullary hemolysis) and a decreased survival of adult RBCs in the peripheral blood. This premature destruction of the thalassemic RBC could in part be due to a loss of phospholipid asymmetry, because cells that expose PS are recognized and removed by macrophages. In addition, PS exposure can play a role in the hypercoagulable state reported to exist in severe beta-thalassemia intermedia. We describe PS exposure in RBCs of 56 comparably anemic patients with different genetic backgrounds of the alpha- or beta-thalassemia phenotype. The use of fluorescently labeled annexin V allowed us to determine loss of phospholipid asymmetry in individual cells. Our data indicate that in a number of thalassemic patients, subpopulations of red cells circulate that expose PS on their outer surface. The number of such cells can vary dramatically from patient to patient, from as low as that found in normal controls (less than 0.2%) up to 20%. Analysis by fluorescent microscopy of beta-thalassemic RBCs indicates that PS on the outer leaflet is distributed either over the entire membrane or localized in areas possibly related to regions rich in membrane-bound alpha-globin chains. We hypothesize that these membrane sites in which iron carrying globin chains accumulate and cause oxidative damage, could be important in the loss of membrane lipid organization. In conclusion, we report the presence of PS-exposing subpopulations of thalassemic RBC that are most likely physiologically important, because they could provide a surface for enhancing hemostasis as recently reported, and because such exposure may mediate the rapid removal of these RBCs from the circulation, thereby contributing to the anemia.

Prenatal and postnatal diagnoses of thalassemias and hemoglobinopathies by HPLC

The conventional approach to qualitative and quantitative analyses of hemoglobin (Hb) molecules for the diagnoses of hemoglobinopathies requires a combination of tests. We used an automated HPLC (VARIANT) system to study alpha-thalassemia and beta-thalassemia syndromes in Thailand. The beta-thalassemia short program is applicable to the diagnosis of alpha-thalassemia and beta-thalassemia disorders, including Hb H, EA Bart's disease, and EF Bart's disease, in adults, newborns, and fetuses. The system cannot quantify accurately certain Hb molecules, such as Hb H and Hb Bart's. The alpha-thalassemia short program was therefore developed and used to quantify Hb Bart's to detect alpha-thalassemia genotypes in cord blood. This automated HPLC system is an alternative approach to the diagnosis of complicated thalassemia syndromes in Thailand and Southeast Asia.

The unusual pathobiology of hemoglobin constant spring red blood cells

Hemoglobin Constant Spring (HbCS) is the most common nondeletional alpha-thalassemic mutation and is an important cause of HbH-like disease in Southeast Asia. HbCS variants have an almost normal mean cell volume (MCV) and the anemia is more severe when compared with other alpha-thalassemic variants. We explored the pathobiology of HbCS red blood cells (RBCs) because the underlying cause(s) of this MCV "normalizing" effect of HbCS and the more severe anemia are not fully explained. HbCS containing RBCs are distinctly overhydrated relative to deletional alpha-thalassemia variants, and the derangement of volume regulation and cell hydration occurs early in erythroid maturation and is fully expressed at the reticulocyte stage. Furthermore, the membrane rigidity and membrane mechanical stability of HbCS containing RBCs is increased when compared with HbH and alpha-thalassemia-1 trait RBCs. In seeking the cause(s) underlying these cellular alterations we analyzed membranes from HbCS and deletional alpha-thalassemic variants and found that in addition to oxidized beta-globin chains, oxidized alpha cs-globin chains are also associated with the membranes and their skeletons in HbCS containing RBCs. We propose that the membrane pathology of HbCS variants is caused by combination of the deleterious effects induced by membrane-bound oxidized alpha cs- and beta-globin chains. The membrane alterations induced by alpha cs chains are more akin to those induced by beta A-globin chains than those induced by the alpha A-globin chains that accumulate in the beta-thalassemias. Thus, each globin chain, alpha cs, alpha A, beta A, appears to produce its own form of membrane perturbation.

The instability of the membrane skeleton in thalassemic red blood cells

The thalassemias are a heterogeneous group of disorders characterized by accumulation either of unmatched alpha or beta globin chains. These in turn cause the intramedullary and peripheral hemolysis that leads to varying anemia. A partial explanation for the hemolysis came our of our studies on material properties that showed that beta-thalassemia (beta-thal) intermedia ghosts were very rigid but unstable. A clue to this instability came from the observation that the spectrin/band 3 ratio was low in red blood cells (RBCs) of splenectomized beta-thal intermedia patients. The possible explanations for the apparent decrease in spectrin content included deficient or defective spectrin synthesis in thalassemic erythroid precursors or globin chain-induced membrane changes that lead to spectrin dissociation from the membrane during ghost preparation. To explore the latter alternative, samples from different thalassemic variants were obtained, ie, beta-thal intermedia, HbE/beta-thal, HbH (alpha-thal-1/alpha-thal-2), HbH/Constant Spring (CS), and homozygous HbCS/CS. We searched for the presence of spectrin in the first lysate of the standard ghost preparation. Normal individuals and patients with autoimmune hemolytic anemia, sickle cell anemia, and anemia due to chemotherapy served as controls. Using gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, no spectrin was detected in identical aliquots of the supernatants of normals and these control samples. Varying amounts of spectrin were detected in the first lysate supernatants of almost all thalassemic patients. The identification of spectrin was confirmed by Western blotting using an affinity-purified, monospecific, rabbit polyclonal antispectrin antibody. Relative amounts of spectrin detected were as follows in decreasing order: splenectomized beta-thal intermedia including HbE/beta-thal; HbCS/CS; nonsplenectomized beta-thal intermedia, HbH/CS; and, lastly, HbH. These findings were generally confirmed when we used an enzyme-linked immunosorbent assay technique to measure spectrin in the first lysate. Subsequent analyses showed that small amounts of actin and band 4.1 also appeared in lysates of thalassemic RBCs. Therefore, the three major membrane skeletal proteins are, to a varying degree, unstably attached in severe thalassemia. From these studies we could postulate that membrane association of abnormal or partially oxidized alpha-globin chains has a more deleterious effect on the membrane skeleton than do beta-globin chains.

Alterations in vascular endothelial cell-related plasma proteins in thalassaemic patients and their correlation with clinical symptoms

An increased level of plasma thrombomodulin (TM) in alpha- and beta-thalassaemia was demonstrated using an enzyme-linked immunosorbent assay (ELISA). Nonsplenectomized patients with beta-thalassaemia/haemoglobin E (BE) had higher levels of TM than splenectomized cases (BE-S). Patients with leg ulcers (BE-LU) were found to have the highest increase in TM level. Appearance of larger platelets in all types of thalassaemic blood was observed indicating an increase in the number of younger platelets. These data indicate that injury of vascular endothelial cells is present in thalassaemic patients.

Hydration of red cells in alpha and beta thalassemias differs. A useful approach to distinguish between these red cell phenotypes

Differences in the pathobiologic features of alpha and beta thalassemic red cells include differing derangements in the ability of these cells to regulate their volume. To explore differences in cell hydration in these two red cell phenotypes, heterogeneity in hemoglobin concentration of individual red cells was quantitated. Red cells from 91 patients with alpha thalassemia (hemoglobin H disease) and 69 patients with beta thalassemia of the genotype beta-thal zero/Hb E were analyzed. Marked differences between these thalassemias were noted in the heterogeneity of hemoglobin concentration among individual cells. Decreased cell hemoglobin concentration and increased cell hydration were features of alpha-thalassemic blood samples, whereas both decreased and increased cell hemoglobin concentration as a result of cell hydration and dehydration, respectively, were features of beta-thalassemic blood samples. The documented differences in the hemoglobin concentration distributions should prove useful in distinguishing between the two thalassemic phenotypes.

Number and maturation of reticulocytes in various genotypes of thalassaemia as assessed by flow cytometry

Ineffective erythropoiesis is a prominent defect leading to anaemic status in thalassaemic patients. Reticulocyte enumeration in the peripheral blood is a non-aggressive method of measuring bone marrow erythropoietic activity. We used an automated reticulocyte counter (Sysmex R-3000) to determine the number and maturation level of circulating reticulocytes among various types of thalassaemia: non-splenectomized beta-thalassaemia/haemoglobin E (beta E) and splenectomized cases (beta E-S), classical haemoglobin H disease (H), haemoglobin H disease with haemoglobin Constant Spring (H/CS), homozygous haemoglobin Constant Spring (CS/CS), homozygous haemoglobin E (EE), heterozygous thalassaemics and other rare combinations. Haemoglobin H disease has a higher absolute count than beta-thalassaemia (beta E), indicating relatively better compensatory erythropoiesis in haemoglobin H disease. Those with CS genes (H/CS and CS/CS) have poorer reticulocyte maturation than any other type of thalassaemia with rather high absolute numbers, especially in H/CS. This indicates a severer degree of ineffective erythropoiesis in beta-thalassaemia (beta E), which reflects an insufficient rise in reticulocyte number in comparison with alpha-thalassaemia (H). The presence of haemoglobin Constant Spring is associated with abnormally low reticulocyte maturation due to enhanced erythrocyte production or direct effect of Constant Spring globin itself, both still unexplained with the current information. The splenectomized beta E has increased reticulocyte number and cells with high DNA content, probably nucleated red cells, designated as the upper particle count parameter. However, there is the same degree of reticulocyte maturation in non-splenectomized and splenectomized beta E patients, suggesting a role for splenic pooling of reticulocytes.

Cytometric analysis of blood cells from malaria-infected patients and in vitro infected blood

Blood samples from malaria-infected patients and from in vitro culture were analyzed using the H*1 hematology analyzer. An attempt to find a hematologic parameter for detecting the malaria infection and to characterize the pathophysiological changes of red cells was made. The study included 18 malaria-infected patients (10 with Plasmodium falciparum and 8 with Plasmodium vivax) and 52 normal, healthy volunteers. Increased young large lymphocyte or large unstained cell count (LUC over 3%) in the peripheral blood of malaria-infected patients was evidence for malaria infection. Increased population dispersions of red cell volume (red cell distribution width: RDW) and intraerythrocytic hemoglobin concentration (hemoglobin distribution width: HDW) were demonstrated both in clinical samples and cultured blood. The increased RDW correlated with an increased percentage of macrocytes (r = 0.64, P = 0.004). Comparison of HDW and percentage of hypochromic red cells between the clinical specimen and the cultured blood supports the finding that changes in red cell hemoglobin concentration were mainly due to the response of the patient to malaria infection and partly due to the effect of malaria parasites on the red cells.

Reduced deformability of thalassemic erythrocytes and erythrocytes with abnormal hemoglobins and relation with susceptibility to Plasmodium falciparum invasion

A number of genetically variant erythrocytes showed decreased deformability of both intact cells and membranes prepared therefrom as measured by laser diffractometry. Erythrocytes associated with minor or no clinical symptoms (eg, alpha-thalassemia traits, hemoglobin [Hb] E trait, Hb Constant Spring trait), which showed only a minimal decrease in deformability, were, in general, invaded efficiently by the malarial parasite Plasmodium falciparum. Other variant erythrocytes (beta-thalassemia/Hb E, homozygous Hb E, homozygous Hb Constant Spring, Hb H, Hb H/Hb Constant Spring) with low deformability showed different degrees of reduction in invasion susceptibility, most of which were less than proportional with deformability decrease. It is concluded that parasite invasion is only weakly related to gross cell deformability, which in turn depends on various factors other than membrane deformability.

Different cell volume with high target cell population between liver disease and homozygous hemoglobin E

Blood samples with increased percentage of target cells were collected from liver disease, thalassemia, homozygous hemoglobin E (E/E), and nonidentified cases. Normal cases who had no history of liver disease and normal hemoglobin typing were also included in the study for control. Patients with liver disease had increased target cell percentage with normal MCV, whereas, the other three groups had increased target cell percentage and reduced MCV. The difference was more obvious when compared with liver disease and homozygous Hb E cases. These two groups had comparable target cell percentage (14.36 +/- 4.77 in liver disease, and 14.22 +/- 1.59 in homozygous Hb E) and comparable degree of anemia (Hb level in liver disease = 11.19 +/- 0.39, and 11.30 +/- 0.16 in homozygous Hb E) but they showed a statistical significance (p less than 0.0001) between MCV (79.66 +/- 2.18 fL in liver disease, and 60.40 +/- 0.75 fL in homozygous Hb E).

Cytochemical reactions of homozygous beta-thalassemic spleens

Splenic cells from 10 homozygous beta-thalassemic patients were stained using cytochemical reactions: non specific esterase and acid phosphatase. Spleens from nonthalassemic subjects: a normal case who underwent gastric surgery and 5 idiopathic thrombocytopenic purpura, were also studied to serve as the control. In thalassemic spleens, no positive dot cell was shown in periarteriolar lymphocyte sheaths (PALS) when they were stained with both nonspecific esterase and acid phosphatase. In contrast, dot positive reaction was demonstrated in 92 per cent of cells from a normal spleen. These cells were presumably T lymphocytes. There were two possibilities to explain our study 1) the absence of T lymphocytes in the PALS of white pulps in homozygous thalassemia may have an impact on the immune system related to infection complication in thalassemia 2) T lymphocytes in the thalassemic spleen may be present but they do not give a positive ANAE dot reaction.

Thalassemic red cells determined by different technology of blood cell analysers

Blood samples from 12 normal cases and 30 thalassemic patients were analyzed by four blood cell analysers (the H*1, Baker 9,000RX, Coulter JT, and Argos). These four machines had different technology: light scattering using laser beam (H*1) and electronic aperture impedance (Baker 9,000RX, Coulter JT, and Argos). Analysis of normal blood samples showed comparable red cell parameters between these four machines except the value of RDW. When the thalassemic blood samples were determined using these four types of blood cell counters, many red cell parameters showed significant difference. This indicates that thalassemic red cells which are known as the abnormal cells in terms of their volume, shape, intracellular hemoglobin content, and osmotic fragility, responded differently to the reagents and technology of blood cell analysis. Calibration of the instrument using qualitatively abnormal blood sample, is recommended.

Measurements of cell volume and hemoglobin concentration of erythrocytes from hereditary ovalocytosis and hereditary spherocytosis

Red cell analysis using the laser technique was done on erythrocytes from 11 cases of hereditary ovalocytosis (HV) and one case of hereditary spherocytosis (HS). Heterogeneity in red cell volume measured as red cell distribution width (RDW) and heterogeneity of hemoglobin concentration in the red cells as measured by hemoglobin concentration distribution width (HDW) were analyzed. All of the studied cases showed abnormal increase in both RDW and HDW. The patient with HS had decreased MCV 77.4 fL (normal range = 80-99 fL). The HS patient had microcytes 14.7 per cent with markedly increased RDW 22.3 per cent (normal range = 11.5-14.5%). Increased hemoglobin concentration was demonstrated in HS red cells as shown by increased CHCM 39.2 g/dl (normal range = 33-37) with 5.86 g/dl of HDW (normal range = 2.2-3.3 g/dl). The HV patients had slightly decreased cell volume, MCV = 84.1 +/- 11.8 fL, with 9.2 +/- 10.1 per cent microcytes and 17.5 +/- 5.7 per cent RDW. Decreased hemoglobin concentration was shown in HV red cells as shown by decreased CHCM (31.7 +/- 1.9 g/dl) with slightly increased HDW (3.3 +/- 0.9 g/dl). The HV patients had increased per cent hypochromic red cells (14.8 +/- 18.6%). The ovalocytic red cells in HV patients had obviously reduced hemoglobin concentration compared to the spherical red cells of HS patients.

Cytometric analysis of paroxysmal nocturnal hemoglobinuria erythrocytes

Erythrocytes from six cases of paroxysmal nocturnal hemoglobinuria (PNH) were analysed by the H*1 hematology analyser using laser inspection for each individual red cell. The computer program categorized the red cells into 9 groups based on the data of red cell volume and intracellular hemoglobin concentration. The only 46.3 +/- 10.9 per cent (Mean +/- SD) of PNH red cells were normochromic normocytic. Hypochromia (hemoglobin concentration less than 28 g/dL) with normal red cell volume (between 60 to 120 fL) were found in 22.8 +/- 19.7 per cent and with large cell volume (greater than 120 fL) = 14.9 +/- 4.5 per cent of total red cells. Large cells with normal hemoglobin concentration were found in 12.9 +/- 13.2 per cent. The red cells had increased heterogeneity in red cell volume measured as red cell distribution width (RDW), Mean +/- SD = 23.6 +/- 2.3 per cent and increased heterogeneity in their hemoglobin concentration distribution with (HDW) (3.4 +/- 0.5 g/dL). The high RDW was resulted from increased number of varying size of macrocytes and the high HDW was caused by the increased number of hypochromic red cells. Heterogeneity in PNH red cell population described in this study has been postulated to relate with the clonal abnormality of the PNH red cells.

An unusual adhesion between red-cells and platelets in falciparum malaria

A Thai female patient infected with P. falciparum had 80 per cent P. falciparum infected red cells at ring stage in the peripheral blood smear. The complications included anemia, thrombocytopenia, acute renal failure and pulmonary edema. A marked decrease in platelets number, low hemoglobin, low hematocrit and decreased red blood cell count were detected. More than 70 per cent of total platelets detected in the blood smear were binding to parasitized red blood cells. The number of binding platelets declined with decreasing per cent parasitized red cells. It was also noted that some platelets (10-20%) adhered to nonparasitized red cells. An increased number of large lymphocytes was shown by increased numbers of large unstained cells (LUC) by H* 1 automated analyzer. The peripheral blood smear showed abnormal binding of platelets to the infected red cells more frequently than to non infected red cells and free platelets on the day of high parasitemia. This abnormal phenomena was related to the number of platelets in the circulation. When the parasitized red cells were not detected in the blood smear, the number of platelets in the circulation had returned to normal.

Effect of vegetable oil intake on erythrocyte physical properties and hemorheology

Effects of vegetable oil intake on red cell physical properties and blood flow condition were evaluated. The study was done on two groups of volunteers taking either soybean oil (6 volunteers) or palm oil (another 6 subjects) for a period of eight weeks. The continuous effects were followed up after continuing the vegetable oil intake for another four weeks. Significant reduction in red cell deformability was demonstrated by laser diffractometry in both groups. The palm oil had greater extent in causing reduced red cell deformability as early as four weeks after the oil intake, whereas, such effect was shown in eight weeks after the soybean oil intake. The reducing effect of red cell deformability by palm oil intake was more obvious than that by the soybean oil intake as indicated by the fall of deformability index from the control by 47.6 per cent in palm oil and 21.9 per cent in the soybean oil group. The decrease still persisted and could be investigated on the four weeks' followup. The hematologic parameters measured by the laser-based instrument, the H*1 analyser were all within the normal ranges in both groups. However, the group taking soybean oil showed decreasing hemoglobin levels, which may be a physiological response to facilitate blood flow condition. The platelet volume was increased in both groups, indicating the possibility of adjustment of thrombopoiesis in the subjects although no clinical indication related to this finding was shown. In conclusion, intake of vegetable oil had an effect on red cell deformability. Soybean oil had an advantage over palm oil in having less effect on reducing the red cell deformability.

Erythrocyte volume and haemoglobin concentration in haemoglobin H disease: discrimination between the two genotypes

Erythrocyte volume and haemoglobin concentration in individual red cells from 62 patients with Hb H disease: 37 with H genotype (alpha-thalassaemia 1/alpha-thalassaemia 2) and 25 H/CS genotype (alpha-thalassaemia 1/Hb Constant Spring) were measured using the H*1 haematology analyser. All 25 cases with H/CS genotype, the more severe genotype, had microcytes (red cells with a volume smaller than 60 fl) less than 35% and hypochromic red cells (red cells with haemoglobin concentration less than 28 g/dl) more than 35%. A discriminant function, the ratio between the percentage of hypochromic red cells and the percentage of microcytes (Hypo/Micro), was proposed. Most of the H/CS patients (76%) had Hypo/Micro greater than 2.5 whereas those of H patients (82%) were below 2.5. Red cell volume histograms were also characteristically different between the two genotypes: the H/CS had a peak between 60 and 90 fl while the H genotype showed a peak at or very close to 60 fl, indicating a greater degree of microcytosis. Increased hypochromia with a slight decrease in cell size of H/CS red cells suggests that the poor degree of haemoglobinization has no linkage or very little role in disturbing the synthesis of membrane proteins and their assembly to the plasma membrane.

Susceptibility to hydrogen peroxide of Plasmodium falciparum infecting glucose-6-phosphate dehydrogenase-deficient erythrocytes

The susceptibility to oxidant-mediated killing of Plasmodium falciparum infecting normal and glucose-6-phosphate dehydrogenase (G6PD)-deficient erythrocytes was assessed by exposure to hydrogen peroxide generated by the glucose-glucose oxidase system. The parasites infecting G6PD-deficient erythrocytes had markedly greater susceptibility to hydrogen peroxide under a variety of conditions than those infecting normal erythrocytes. In both cases, the killing effect was mediated mainly through the host cells since treatment of the erythrocytes with hydrogen peroxide did not change their relatively susceptibility. The parasites were most susceptible during maturation, especially in G6PD-deficient erythrocytes, although a reduction in parasite invasion was also observed. The role of oxidant-mediated killing in the protection of G6PD-deficient hosts from P. falciparum infection is discussed.

Analysis of hematological data of thalassemia cases in Thailand

We analyzed the complete blood count (CBC) obtained from patients with various types of thalassemia in Thailand. As a control, samples from healthy donors and patients with iron deficiency anemia were also collected. Most cases of thalassemia could be differentiated from iron deficiency anemia by using a discrimination function equation. This screening method is applicable for mass-screening of patients with latent thalassemia in Thailand.

Increased ovalocytic red cells and their low parasitemia in malaria infected subjects

Ovalocytic red blood cells were significantly increased in the peripheral blood films of patients infected with P. falciparum (mean +/- S.D. = 6.3 +/- 8.4%) and P. vivax (8.3 +/- 14.0%), whereas, there was only 0.6 +/- 0.4 per cent ovalocytes in normal individuals. Per cent parasitemia of ovalocytes counted at least 100 ovalocytes of the blood films of malaria infected individuals was significantly reduced when compared with that of discocytes which revealed at least 100 discocytes in the same blood smears. Relative increase in ovalocyte and their low parasitemia might be the response of malaria infected individuals to cope with malaria multiplication in their circulation.

Decreased sensitivity of artesunate and chloroquine of Plasmodium falciparum infecting hemoglobin H and/or hemoglobin constant spring erythrocytes

Plasmodium falciparum infecting hemoglobin (Hb) H and/or Hb Constant Spring erythrocytes in vitro was relatively more resistant than that infecting normal erythrocytes to artesunate and chloroquine, while the sensitivity to pyrimethamine was unchanged. The 50% inhibitory concentrations (IC50) for artesunate in HbH (alpha-thal 1/alpha-thal 2), HbH (alpha-thal 1/Hb Constant Spring), and homozygous Hb Constant Spring erythrocytes were 4.5 +/- 2.8, 8.5 +/- 3.2, and 2.6 +/- 1.6 nM compared with 0.82 +/- 0.35 nM in normal erythrocytes (P less than 0.002 for all three cases). The IC50 for chloroquine were 97 +/- 46, 162 +/- 67, and 93 +/- 36 nM, respectively, in the variant erythrocytes, compared with 48 +/- 13 nM in normal erythrocytes (P less than 0.002, 0.002, and 0.02, respectively). The differences in sensitivity to artesunate and chloroquine of the parasite infecting HbH erythrocytes are probably related to their oxidative mode of action and relatively high amounts of antioxidant enzymes in the host erythrocytes. This novel example of dependence on the host of the malarial parasite drug sensitivity may have implications for chemotherapy of malaria in patients with genetically variant erythrocytes.

Cytochemical evaluation of neutrophil components in beta thalassemia hemoglobin E

The mean +/- S.D. of LAP score in neutrophil of the normal control, non splenectomised patients and splenectomised patients were 116 +/- 78, 94 +/- 48 and 37 +/- 23 Kaplow units, respectively. The significant reduction in the leukocyte alkaline phosphatase level (P less than 0.05) was found in beta thalassemia/HbE patients. The degree of reduction was greater in the splenectomised patients (P less than 0.05). The decreased LAP levels in PMN was persistent. This was in contrast to the LAP in PMN of other patients where as LAP returned to normal after splenectomy. The relevance to the increased susceptibility to infection and low LAP in beta thalassemia/HbE should be further investigated.

Impaired parasite growth and increased susceptibility to phagocytosis of Plasmodium falciparum infected alpha-thalassemia or hemoglobin Constant Spring red blood cells

In vitro multiplication of Plasmodium falciparum in hemoglobin H or hemoglobin Constant Spring red blood cells (from homozygotes or double heterozygotes) was significantly reduced as compared with that in normal erythrocytes. The parasitized genetically abnormal red blood cells showed furthermore a high propensity for being phagocytosed by peripheral blood monocytes. Both impaired parasite growth and increased susceptibility to phagocytosis may be related to mechanisms for protection of the variants from P. falciparum infection.

Inhibitory effect of beta zero-thalassaemia/haemoglobin E erythrocytes on Plasmodium falciparum growth in vitro

The growth of Plasmodium falciparum in erythrocytes from individuals with beta zero-thalassaemia or haemoglobin (Hb) E, or both, was assessed in vitro. A significant inhibitory effect on the growth of the parasite was found only with erythrocytes from individuals doubly heterozygous for beta zeros-thalassaemia and HbE. The inhibitory effect was particularly marked with erythrocytes from splenectomized beta zeros-thalassaemia/HbE patients. The protective effect was related to HbF, Hb levels and shape abnormalities of the variant erythrocytes.

Use of tartaric acid resistance of beta-glucuronidase for the characterization of cancer cells in pleural effusions

Tartaric acid was shown to have an inhibiting effect on beta-glucuronidase staining in mesothelial cells and macrophages but not in malignant cells in pleural effusions. Staining for beta-glucuronidase with tartaric acid inhibition is thus suggested for the differentiation of cancer cells from mesothelial cells and macrophages in effusions.

Defective spectrin dimer self-association in thalassemic red cells

The relative proportions of spectrin tetramer and dimer forms extrated from red cell membranes in a low ionic strength buffer at 4 degrees C were determined for 15 normal subjects, 27 subjects with alpha-thalassemia (7 alpha-thalassemia trait, 9 Hb H disease (alpha-thal 1/alpha-thal 2) and 11 Hb H with Hb Constant Spring (CS), 23 subjects with beta-thalassemia (6 beta-thalassemia trait, 5 homozygous beta-thalassemia, 11 beta(0)-thalassemia with Hb E and 1 beta(+)-thalassemia with Hb E), 6 subjects with Hb E (2 homozygous and 4 carriers) and 1 subject with combined alpha-thal 1/Hb CS and Hb E (AE Bart's disease). In all subjects (except carriers of Hb E and 1 splenectomized case of beta(0)-thal/Hb E) spectrin dimer forms were elevated when compared to levels in normal controls, but there were no significant differences between carrier and disease forms. Conversion of spectrin dimers to tetramers at 30 degrees C was reduced in the thalassemic subjects with disease but was within normal range for thalassemic carriers.

Immunization with a live attenuated dengue-2-virus candidate vaccine (16681-PDK 53): clinical, immunological and biological responses in adult volunteers

A live dengue-2 (DEN-2) candidate vaccine (strain 16681-PDK 53), attenuated by passage in primary dog kidney cells, was tested in ten adult volunteers for evaluation of the safety, infectivity and immunogenicity of a dose of 1.9-2.7 x 10(4) plaque-forming units. Five of the volunteers were nonimmune to either dengue or Japanese encephalitis (JE) viruses; the other five were nonimmune to dengue but immune to JE. After receiving 1.0 ml of the vaccine subcutaneously, all ten volunteers developed neutralizing antibodies to DEN-2 which were maintained for at least one and a half years. None of the subjects developed abnormal signs or symptoms and the results of clinical chemistry investigations were within normal range throughout the 21 days of observation after the immunization. Virus isolated from one viraemic volunteer retained the small-plaque and temperature-sensitive growth characteristics of the vaccine virus in vitro. Further testing of this candidate vaccine in humans is indicated.