Growth of erythroid cells from thawed unseparated cord blood in vitro without exogenous erythropoietin.

INTRODUCTION: Previous erythroid cell cultures have depended on added serum or erythropoietin. In this paper, the growth of erythroid cells from thawed unseparated cord blood units in vitro without serum or exogenous erythropoietin is reported. METHODS: Thawed volume-reduced cord blood was cultured in conditions designed to support the megakaryocytic lineage, with thrombopoietin and interleukins 3 and 6. Erythroid cells were detected with glycophorin A (GlyA), CD71, and benzidine (flow cytometry and immunocytochemistry). RESULTS: Nucleated and anucleated GlyA-positive, as well as benzidine-positive cells were observed from day 9. In flow cytometry, at days 0 and 9, 5.9% and 14% of all events were GlyA+, and 14% and 53% were CD71+, respectively. At days 0 and 9, 4.5% and 12% of the events were double-positive for GlyA and CD71, respectively. By day 14, the percentages of GlyA+, CD71+ and double-positive events had started to decrease (9.7%, 35%, and 5.3%, respectively). CONCLUSIONS: Erythroid cells were generated from thawed unseparated cord blood units without exogenous erythropoietin. Thawed cord blood possesses the potential for erythroid growth in vitro in a culture medium designed for other cell types.

Fetal intracranial haemorrhages caused by fetal and neonatal alloimmune thrombocytopenia: an observational cohort study of 43 cases from an international multicentre registry.

OBJECTIVE: To characterise pregnancies where the fetus or neonate was diagnosed with fetal and neonatal alloimmune thrombocytopenia (FNAIT) and suffered from intracranial haemorrhage (ICH), with special focus on time of bleeding onset. DESIGN: Observational cohort study of all recorded cases of ICH caused by FNAIT from the international No IntraCranial Haemorrhage (NOICH) registry during the period 2001-2010. SETTING: 13 tertiary referral centres from nine countries across the world. PARTICIPANTS: 37 mothers and 43 children of FNAIT pregnancies complicated by fetal or neonatal ICH identified from the NOICH registry was included if FNAIT diagnosis and ICH was confirmed. PRIMARY AND SECONDARY OUTCOME MEASURES: Gestational age at onset of ICH, type of ICH and clinical outcome of ICH were the primary outcome measures. General maternal and neonatal characteristics of pregnancies complicated by fetal/neonatal ICH were secondary outcome measures. RESULTS: From a total of 592 FNAIT cases in the registry, 43 confirmed cases of ICH due to FNAIT were included in the study. The majority of bleedings (23/43, 54%) occurred before 28 gestational weeks and often affected the first born child (27/43, 63%). One-third (35%) of the children died within 4 days after delivery. 23 (53%) children survived with severe neurological disabilities and only 5 (12%) were alive and well at time of discharge. Antenatal treatment was not given in most (91%) cases of fetal/neonatal ICH. CONCLUSIONS: ICH caused by FNAIT often occurs during second trimester and the clinical outcome is poor. In order to prevent ICH caused by FNAIT, at-risk pregnancies must be identified and prevention and/or interventions should start early in the second trimester.

Association of stress-related perinatal factors and cord blood unit hematopoietic progenitors is dependent on delivery mode.

BACKGROUND: Perinatal characteristics, variably utilized in cord blood (CB) selection for banking, affect CB hematopoietic progenitor cells (HPCs). The association between perinatal stress factors and CB unit HPCs was evaluated. STUDY DESIGN AND METHODS: Umbilical arterial (UA) pH, absolute and relative birth weight (BW) and placental weight (PW), and PW/BW ratio of 167 healthy, full-term infants were compared with CB unit prefreeze total nucleated cells (TNCs), total CD34+ (TCD34+) cells, and total colony-forming unit (CFU-TOT) number. Cesarean section (C-section, n = 104) and vaginal delivery subgroups were also analyzed. RESULTS: UA pH (median, 7.28; range, 7.04-7.40) correlated with CB unit CFU-TOT number (n = 166; r = -0.32, p < 0.0001), TCD34+ cells (r = -0.31, p < 0.0001), and TNCs (r = -0.29, p = 0.0002). Similarly, BW, PW, and PW/BW ratio correlated with HPCs. In multiple linear regression analysis, CFU-TOT number was predicted by collected CB TNCs and UA pH in vaginal deliveries (R(2) = 0.53), in contrast with TNCs, PW, and BW in C-sections (R(2) = 0.37). TCD34+ cells were predicted by adding UA pH (vaginal deliveries, R(2) = 0.75) or PW (C-sections, R(2) = 0.36) to collected CB TNCs. CONCLUSIONS: Stress-related perinatal factors, particularly UA pH, are associated with CB unit HPCs and may improve unit selection. Multiple linear regression models may prove useful for predicting HPCs. Mode of delivery affects model choice; UA pH has a strong effect on HPCs in vaginal deliveries.

Significance of quantitative measurement of heparin-induced platelet antibodies.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a prothrombotic immune-mediated adverse drug reaction. Antigen and platelet activation assays are used for detection of antibodies. Quantitative results from platelet factor 4 (PF4)-dependent immunoassays may lead to inter-laboratory standardization of measurements. OBJECTIVES: The aim was to modify a PF4-dependent immunoassay to measure PF4/heparin antibodies quantitatively. METHODS: Over five consecutive years, 1070 samples from thrombocytopenic, heparin-treated patients were analyzed by a PF4/heparin ELISA and the heparin-induced platelet activation assay (HIPA). Results of ELISA assay were expressed as arbitrary units per liter (AU/L). RESULTS: Precision of ELISA at the concentration of 50 AU/L was 3.6%. Of 1070 samples, 117 were positive for antibodies by ELISA and/or HIPA assay. The higher the antibody concentration was, the higher was the proportion of HIPA positive cases (>140 AU/L, 100%, n = 26; 100-140 AU/L, 55%, n = 20; 50-99 AU/L, 38%, n = 29; 30-49 AU/L, 17%, n = 36). CONCLUSIONS: The measurement of anti-PF4/heparin antibody concentration is a new parameter that may improve the diagnosis of HIT. All samples with extremely strong antibody concentration were positive also by HIPA. For accuracy, antibody concentrations must be in the linear range of the assay and an international standard is needed.

Alloantibodies against low-frequency human platelet antigens do not account for a significant proportion of cases of fetomaternal alloimmune thrombocytopenia: evidence from 1054 cases.

BACKGROUND: Maternal alloantibodies against the five common human platelet antigen (HPA) systems (HPA-1 to -3, -5, and -15) are found in only 20% of cases referred for fetal and neonatal thrombocytopenia (FMAIT) investigations. The question asked was whether mismatches for the remaining 11 low-frequency HPAs (HPA-4 and -6bw to -17bw) might in part explain the remaining 80% of cases. STUDY DESIGN AND METHODS: A total of 1054 paternal DNA samples from referred FMAIT cases (among which 223 cases where antibodies against a common HPA were found) were genotyped for 11 low-frequency HPAs as well as a recently discovered polymorphism (ITGA2B-C2320T). The initial genotyping was carried out by TaqMan and potential heterozygotes were confirmed by DNA sequencing. Clinical and serologic data were collected for each case with a heterozygote father. RESULTS: In total, eight heterozygous fathers were identified: four for HPA-6w, one each for HPA-10w and -11w, and two for HPA-12w. Maternal antibodies against the corresponding antigen were identified in four of the eight cases. In two of these cases, antibodies against HPA-1a and HPA-1b were also found. CONCLUSION: It was concluded that the minor alleles of HPA-4 and -6bw to -17bw are exceptionally rare in the Caucasian population and therefore do not explain the large number of FMAIT referrals which test negative for the common HPA antibodies.

A single-nucleotide polymorphism in the human ITGB3 gene is associated with the platelet-specific alloantigen Va (HPA-17bw) involved in fetal maternal alloimmune thrombocytopenia.

BACKGROUND: The previously reported platelet (PLT)-specific antigen, Va(a), was defined by an alloantibody detected in the serum sample of a mother who delivered an infant displaying symptoms of severe fetal maternal alloimmune thrombocytopenia (FMAIT). This PLT antigen was localized to the integrin alphaIIbbeta3 (GPIIbIIIa) but its genetic basis was not defined. STUDY DESIGN AND METHODS: Genomic ITGA2B (alphaIIb) and ITGB3 (beta3) DNA from a Va(a)-positive individual were sequenced to identify potential polymorphisms underlying the Va(a) antigen. Recombinant beta3 integrin carrying the putative mutation was then used to assess serologic reactivity with the original maternal Va(a) antiserum. RESULTS: A single-nucleotide polymorphism (SNP; C622>T) in exon 5 of ITGB3 resulting in the replacement of threonine with methionine at residue 195 of the mature beta3 was identified. Calmodulin-tagged soluble recombinant beta3 encoding Met195 was produced in S2 cells and found to react specifically with the Va(a) antiserum. CONCLUSION: With the use of a combination of DNA sequencing and recombinant antigen expression, the molecular basis of the PLT-specific Va(a) antigen (HPA-17bw), a low-frequency antigen implicated in FMAIT, has been resolved. These data further demonstrate the value of using recombinant beta3 peptides for the detection of rare but clinically relevant antibodies.

Association of cord blood platelet characteristics and hematopoietic progenitor cells.

BACKGROUND: Total nucleated cell (TNC) dose is associated with neutrophil and platelet (PLT) engraftment after cord blood (CB) transplantation and thus is used for selection of CB for banking. The goal of this study was to evaluate the internal relationships of CB PLT characteristics, TNC, and the hematopoietic progenitor cell (HPC) content of CB units. STUDY DESIGN AND METHODS: HPC and TNC counts of 167 CB units processed with an automated cell separation system were compared with CB PLT count and mean PLT volume (MPV). Megakaryocyte progenitors (CFU-MK) were cultured from a subset of units (n = 24). RESULTS: PLT concentration correlated with MPV (r = -0.39), which was also associated with both TNC and total CD34+ cells before and after processing (r = 0.37 and 0.35 and r = 0.41 and 0.42, respectively). In addition, MPV was associated with HPC counts in the CB unit. The p value was less than 0.001 for all associations. PLT count was inversely associated with markers of hematopoietic potential. Median removal of PLTs during processing was 62 percent (range, 40%-84%). All 24 CB units of the subset exhibited CFU-MK growth. In multivariate linear regression analysis, MPV improved prediction of the HPC content of the CB unit compared to prediction with CB volume and nucleated cell concentration only. CONCLUSION: Mean PLT volume correlated with current markers of CB hematopoietic potential and is potentially useful for evaluating CB collections for banking. The question of the clinical significance of PLT characteristics in CB transplantation remains unanswered.

Discarded cellular components and the technical efficiency of component preparation.

Given increasing cost pressures, the need to improve the technical efficiency of the production chain used for collected blood in blood banking should be recognised. Data envelopment analysis (DEA) was used to study the relationship between discard rates and technical efficiency. Whole-blood (WB) collections, aphaeresis-platelets, produced and discarded red blood cells (RBCs) and platelets (PLTs) were included in the analyses. Technical efficiency tended to be higher when the proportion of the total of RBC and PLT discards from WB collections was low. In DEA modelling, the choice of relevant input and output variables is one of the most important factors affecting the validity of the results. Discarded components should not be ignored in analyses of efficiency, because lost production output also has monetary value.

Viability does not necessarily reflect the hematopoietic progenitor cell potency of a cord blood unit: results of an interlaboratory exercise.

BACKGROUND: Clinical transplant outcome with umbilical cord blood (UCB) as source of hematopoietic progenitor cells (HPCs) is, among other factors, determined by the total number of viable nucleated cells and/or CD34+ cells in the unit. Quantitative and qualitative losses by processing and cryopreservation and by thawing and washing before transfusion may occur, however. Another reason for a discrepancy between the number of cells in the unit released by the cord blood bank and found in the transplant center may be technical differences in cell counting methods between the two sites. STUDY DESIGN AND METHODS: With the collaborative group for Biomedical Excellence for Safer Transfusion (BEST), an interlaboratory exercise was conducted among nine sites for thawed UCB variables: total nucleated cells, CD34+ cells, viability, and HPC cultures. Three frozen UCB samples were shipped, with instructions for thawing, counting, and HPC plating. RESULTS: Unexpectedly samples arrived at all nine receiving centers without detectable hematopoietic progenitor colony-forming cells. Nevertheless, wide interlaboratory ranges for viability were obtained. The proportion of viable cells was found higher with manual methods, but all viability assays used in the study overestimated functional progenitor cells. CONCLUSIONS: The results underscore the complexity of evaluation of frozen-thawed cord blood cells and the need for standardization of assessment.

International comparison of the technical efficiency of component preparation.

BACKGROUND: Under economical constraints, blood centers need to identify ways to improve their efficiency. Because there is little evidence regarding the technical efficiency of blood centers, international comparisons may be useful in identifying efficiency discrepancies and can reveal opportunities for enhancing efficiency, such as allocating resources more effectively. STUDY DESIGN AND METHODS: Data were collected for years 2000 through 2002 from 16 blood centers in 10 European countries. Input variables included working hours, whole-blood (WB) collections, premises, and equipment, and the output variables were red blood cells and platelets (PLTs). A nonparametric method, data envelopment analysis (DEA), was used in the analyses of technical efficiency in blood component preparation departments. Efficiency scores were calculated with DEA linear programming techniques and evaluated for site characteristics that possibly affect efficiency, such as the production method of PLTs and the proportion of BCs (buffy coats) from WB and BC PLTs from all PLTs produced. RESULTS: With working hours and equipment as inputs, median technical efficiency was 60 percent (range, 41%-100%). Four departments were efficient (efficiency, > 90%), and 12 were inefficient (range, 41-89). Efficiency remained roughly the same in 13 departments through the 3-year study period and decreased in 3. Efficiency was mainly affected by staffing levels (working hours). Efficiency did not directly relate to production volume, method, or any other site characteristic. CONCLUSIONS: The major cause of inefficiency was excess staffing resulting from a suboptimal combination of manpower and production output levels. Further research is needed to manage factors affecting efficiency, such as the fluctuation of demand in production planning.

Variation of platelet production and discard rates in 17 blood centers representing 10 European countries from 2000 to 2002.

BACKGROUND: New blood safety regulations raise costs and pressure blood centers to improve their efficiency. Evaluation of platelet (PLT) production and discards between centers of different size and nationality may provide a basis for more efficient PLT inventory management. STUDY DESIGN AND METHODS: Data were gathered retrospectively for 2000 to 2002 from 17 blood centers in 10 European countries. The descriptive analyses comprised evaluation of PLT production methods and volumes. Discard rates were surveyed also for 2003 to 2004. The number of cellular blood components produced per working hour was expressed as an arbitrary labor index. RESULTS: Seven hospital blood banks and 10 centers with other administrative systems participated in the study. Buffy coat (BC) and apheresis PLTs were used by all centers except two preparing all PLTs by apheresis. In 2002, 73 percent of all PLTs were produced by the BC method, and PLTs were utilized from 41 percent of whole-blood donations. One center also produced PLTs by the PLT-rich plasma method. Mean annual production volume of PLTs varied greatly, from 3,345 to 103,643 units, with an increase of 5.6 percent from 2000 to 2002. Three-year mean discard rates varied between 6.7 and 25 percent, and yearly mean discard rates remained at 13 percent in 2000 to 2002 and also in 2003 to 2004. Arbitrary labor index varied from 2.4 to 7.3 between centers. CONCLUSIONS: PLT discard rates were relatively high in the European blood centers. Detailed information on specific causes for high discard rates would help improve the efficiency of PLT management, because blood centers cannot regulate demand. Use of labor resources in component preparation also remains an important target for further research.

Multiple-laboratory comparison of in vitro assays utilized to characterize hematopoietic cells in cord blood.

BACKGROUND: Understanding the variability in results obtained by multiple laboratories is important because cord blood units are distributed worldwide for transplantation. STUDY DESIGN AND METHODS: Four exercises were conducted by multiple laboratories to assess assay variability on nucleated cell (NC), mononuclear cell (MNC) by hematology analyzers [HAs], and CD34+ cell (flow cytometry) measurements. Exercise 1 was an intralaboratory exercise in which the reproducibility of cell measurements was determined. Exercises 2 and 3 involved the shipment of identical processed cord blood samples. In Exercise 2, laboratory-specific methods were utilized. In Exercise 3, two commercial CD34+ cell methods (Stem-Kit and TruCOUNT) were used. In Exercise 4, CD34+ cell levels were determined on repetitive regating of identical list-mode files. RESULTS: Intralaboratory reproducibility was highest for NC measurements and lowest for CD34+ cell measurements. In Exercise 2, all laboratories except one utilized HA with an impedance technology and determined comparable results for NC and MNC levels, whereas the other laboratory utilized a HA with an optical counting method. Substantial variation was observed on measuring CD34+ cells with ranges of 32 to 141, 32 to 66, and 25 to 116 CD34+ cells per microL for the three identical samples. In Exercise 3, on the use of one specific commercial assay, the ranges of CD34+ levels were 214 to 411 and 62 to 178 cells per microL for the two identical samples. Nearly all participating laboratories determined comparable CD34+ levels on the use of identical list-mode files. CONCLUSION: These studies indicate that substantial variability in CD34+ cell levels were determined with flow cytometry. The variability in NC and MNC levels was minimal with HA methodology.

A common ancestral glycoprotein (GP) 9 1828A>G (Asn45Ser) gene mutation occurring in European families from Australia and Northern Europe with Bernard-Soulier Syndrome (BSS).

Bernard-Soulier syndrome (BSS) is an extremely rare hereditary bleeding disorder, caused by mutations occurring in the Glycoprotein (GP) Ibalpha, GPIbbeta and GP9 genes that encode for the corresponding subunits of platelet GPIb-V-IX adhesion receptor complex. BSS has been reported in many populations, mostly behaving in an autosomal-recessive manner.While the great majority of BSS mutations are unique to a single individual or family, the GP9 1828A>G Asn45Ser mutation, which we have identified in an undocumented Australian Caucasian, has already been reported in multiple unrelated Caucasian families from various Northern and Central European countries. Haplotype analysis of 19 BSS patients from 15 unrelated Northern European families (including 2 compound heterozygote siblings from a British family previously published, and 17 1828A>G Asn45Ser homozygotes), showed that 14 of these BSS patients from 11 of the 1828A>G Asn45Ser homozygote families share a common haplotype at the chromosomal region 3' to the GP9 gene. Hence, the results suggest that the GP9 1828A>GAsn45Ser mutation in these families is ancient, and its frequent emergence in the European population is the result of a founder effect rather than recurrent mutational events. Association of the 1828A>G Asn45Ser mutation with variant haplotypes in 4 other Northern European BSS families raised the possibility of a second founder event, or rare recombinations in these families. Additional members from these 'atypical' lineages would need to be screened to resolve this question.

Intraventricular haemorrhage in very-low-birthweight preterm infants: association with low prothrombin activity at birth.

AIM: To determine the occurrence of intraventricular haemorrhage (IVH) and its association with coagulation factors at birth in preterm neonates born before 30 wk gestation. METHODS: 38 neonates (median gestational age 27 wk, range 24-29 wk; median birthweight (BW) 933 g, range 515-1760 g) admitted to the neonatal intensive care unit were studied. Blood samples for coagulation factors were taken within 2 h after birth. The first cranial ultrasonographic examination was performed within the first 3 d. The occurrence of IVH was tested statistically by the Mann-Whitney U-test for association with the activity of coagulation factors and clinical variables. RESULTS: Thirteen IVHs occurred within the first 3 d of life. IVH was associated with BW <1000 g (p=0.012), low mean blood pressure within the first 2 d (p=0.026), gestational age <27 wk (p=0.054), low Apgar scores (<7) at 1 min (p=0.078) and intrauterine growth restriction (p=0.072). At birth (samples drawn with a median of first 36 min of life), infants with subsequent IVH had statistically significantly lower prothrombin (factor II) activity (p=0.024) than infants without IVH. CONCLUSION: The measured low prothrombin may have been affected by a prior bleeding event. Nevertheless, preterm infants with low prothrombin activity may be susceptible to IVH, or to the progression of it, if left undiagnosed.

Soluble glycoprotein V as a quality marker of platelet concentrates stressed by transportation.

BACKGROUND: Despite ongoing improvements in storage conditions for platelet concentrates (PCs) for clinical use, leukoreduced platelets (PLTs) undergo subtle changes that are partly due to PLT activation. As PLTs are activated, the expression of P-selectin (CD62P) increases, and soluble glycoprotein V (sGPV) is released. GPV, part of the GPIbIXV complex, has been suggested as a marker of PLT activation. STUDY DESIGN AND METHODS: An array of assays, used for quality control of PCs, was performed and the results were compared. The tests included PLT count, swirling, mean PLT volume, extent of shape change (ESC), hypotonic shock response (HSR), CD62P, lysosomal membrane protein (CD63), sGPV, and the metabolic tests (pH, pO(2), pCO(2), lactate, glucose). The performance of the assays was evaluated during the storage period by comparing buffy coat-derived PCs (24 PCs of 4 units) stored on flatbed agitator or stressed twice by overnight transportation. RESULTS: The repeatability of all tests was good. ESC and HSR correlated with each other (r = 0.559). Importantly, there were also associations between sGPV and ESC (r = -0.564) and HSR (r = -0.389). The correlations of sGPV with lactate and glucose concentrations and with expression of CD62P and CD63 were also good. No significant changes were induced by two overnight transportations. CONCLUSION: sGPV might be applicable for statistical process control of the quality of PCs, in addition to metabolic tests. It may also be helpful in analyzing potential improvements in blood component processing. Repeat transportation of PCs may cause minimal changes on PLT in vitro properties, if any.

Cord blood hematopoietic progenitor cell concentration and infant sex.

BACKGROUND: Characterization of cord blood facilitates understanding of the factors affecting cord blood transplant quality and improvement of transplantation results. Cord blood obtained from male and female infants has not been thoroughly characterized. STUDY DESIGN AND METHODS: A study was performed to test the hypothesis that the cord blood hematopoietic progenitor cell content-of which the CD34+ cell and colony-forming unit (CFU) concentrations were taken as markers-would not only associate with birth weight but also with sex. The hematopoietic progenitor cell concentrations of 1999 healthy infants (47% female) were analyzed in a cord blood bank setting. RESULTS: Male infants had significantly higher median CD34+ cell concentrations than female infants (31.8/microL vs. 30.2/microL, respectively; p = 0.03). Although the disparity in absolute concentrations was small, it was 5.3 percent. In CFU subgroup analysis, the median CFU-mixed concentration of male infants (11.1/microL) was higher than in female infants (9.9/microL; p = 0.03). The difference was more pronounced when cumulative frequencies of the CFU-mixed concentrations from cesarean section deliveries were compared. In multivariate linear regression analysis, the positive influence of male sex on the CD34+ cell concentration was significant (p < 0.05). The expected higher median nucleated cell concentration of female compared to male infants (13.9 x 10(9)/L vs. 13.3 x 10(9)/L, respectively; p = 0.0001) was mainly due to the higher neutrophil concentration of female infants (7.1 x 10(9)/L vs. 6.5 x 10(9)/L, respectively, p < 0.0001). CONCLUSION: Cord blood hematopoietic progenitor cell concentration was higher in male infants, even after correcting for birth weight. Sex may affect the hematopoietic potential of cord blood transplants.

Development of selected coagulation factors and anticoagulants in preterm infants by the age of six months.

The development of the coagulation and anticoagulation system in preterm infants was assessed, with special emphasis on extremely low birth weight (ELBW) infants and haemorrhagic or other complications after birth. Coagulation factors II (prothrombin), V (FV), VII (FVII) and X (FX) were analysed at birth and at a corrected age of six months. In addition, antithrombin (AT), protein C (PC) and protein S (PS) were measured at six months, and DNA samples were tested for Factor V Leiden (R506Q). Eighty-two infants, with a median gestational age (GA) of 32 weeks (range 24-36) and a median birth weight of 1562 g (range 695-3520), were studied. Fifteen of these were ELBW infants (range 695-1000g). Prothrombin, FV, FVII and FX reached healthy term six-month-old infant activity levels. Prothrombin and FX did not reach adult values; median activity levels remained at 82% and 78%, respectively. During the follow up, the FV and FVII levels of the ELBW infants (GA 24-27 weeks) increased more than those of the preterm infants born with higher GA (p < 0.001). At birth, prothrombin correlated significantly with FV, FVII and FX (p < 0.001). FVII at birth and at six months correlated significantly with PC (p = 0.021 and p = 0.009, respectively). These findings indicate that the gain in the coagulation factor concentrations in infancy is greatest in infants with the lowest GA at birth. Interesting new inter-relations of coagulation factor and physiological anticoagulant levels may indicate that there are still unrecognised pathways in the function of newborn haemostasis.

Multicenter evaluation of a whole-blood filter that saves platelets.

BACKGROUND: Whole-blood (WB) leukoreduction filters in current use retain the majority of PLTs. A new whole-blood filter, which retains significantly fewer of the PLTs (or saves PLTs [WB-SP]), has been developed. The performance characteristics of the WB-SP filter have been evaluated in a multicenter study. STUDY DESIGN AND METHODS: A total of 617 units of WB was collected into quadruple bag sets with an integrated WB-SP filter, leukoreduced, and processed into leukoreduced RBCs (LR-RBC), plasma (LR-PL), and buffy coats (LR-BC) from which, pooled, leukoreduced, PLT concentrates (LR-PCs) were produced. Recovery, yield, and residual WBCs were assessed in prepared blood components. RESULTS: The median residual WBC number in the LR-RBCs was 0.05 x 10(6) (range, <0.05-3.8), exceeding 1 x 10(6) in 0.6 percent of the units. Median Hb content in LR-RBC was 50 g (range, 34-72), reflecting a final RBC recovery of 81 +/- 6 percent. The median WBC content of the LR-PC was 0.05 x 10(6) (range, <0.05-0.28), with none exceeding 1 x 10(6). The median PLT content of the LR-PC, per individual donation, was 6.4 x 10(10) (range, 4.1-10.7), representing a final recovery of 62 +/- 10 percent. The mean FVIII activity was 104 +/- 25 percent and 83 +/- 11 percent in plasma separated from fresh or overnight stored WB, respectively. CONCLUSION: Use of the WB-SP filter makes it possible to obtain three leukoreduced blood components with only one filtration step. The WB-SP filter showed good leukoreduction performance and recovery of all blood components including PLTs.

The predictive value of megakaryocytic and erythroid colony formation and platelet function tests on the risk of thromboembolic and bleeding complications in essential thrombocythaemia.

The predictive value of spontaneous in vitro colony formation of megakaryocytic and erythroid progenitors (154 patients), and defective platelet aggregation responses (55 patients) on the risk of thrombohaemorrhagic complications in patients with essential thrombocythaemia (ET) was evaluated retrospectively. In the in vitro cultures of haematopoietic progenitors, 114/154 patients (74%) showed either spontaneous megakaryocytic or erythroid colony formation or both. Forty-three per cent of patients with any spontaneous colony growth and only 20% of those without this phenomenon had an arterial thrombosis at diagnosis or during the follow-up (P = 0.02). In the whole patient group neither spontaneous megakaryocytic nor spontaneous erythroid colony formation alone predicted the risk of arterial thrombosis. In patients younger than 45 yr of age, the prognostic value of spontaneous megakaryocytic growth was statistically significant: 44% of the patients with spontaneous megakaryocytic colony formation, but only 14% of those without it, experienced arterial thrombosis (P = 0.04). The presence of spontaneous colony formation had no effect on the risk of bleeding complications. Forty-one of the 55 patients (75%) showed abnormalities in the platelet aggregation responses. There was no statistically significant correlation between the platelet function response and the risk of bleeding or thrombotic complications. No correlation was found between the platelet aggregation responses and the presence of spontaneous colony growth. In conclusion, spontaneous colony formation indicated an increased risk of thrombohaemorragic events but the platelet function test had no predictive value for these complications.

Platelet function and immune response.

Altered platelet function may cause abnormal bleeding tendency or thrombosis. The goal of this article is to provide insights for understanding how platelet functions are related to immune response. Autoantibodies and drug-induced platelet antibodies have been demonstrated to downregulate or enhance platelet function. Drug-induced immune thrombocytopenia is an important adverse effect of glycoprotein IIb/IIIa antagonists. Platelets respond to binding of glycoprotein IIb/IIIa by partial platelet activation. This includes conformational changes of glycoprotein IIb/IIIa. Membrane changes may expose immunogenic neoantigens capable of abnormally altering immune responses. The presence of drug-dependent antibodies in an unexpectedly high frequency compared with the frequency of overt thrombocytopenia has opened a model for further studies. These may include monitoring of antiplatelet immune responses when new platelet antagonists are developed and comparisons of specific immune responses in other acute thrombocytopenias, such as those induced by quinidine or heparin and that associated with gold therapy or in acute profound thrombocytopenia, which may follow vaccination with live attenuated viruses.