Haemophilic arthropathy: basic protocols for clinical examination and imaging.

In haemophilia, screening protocols in the prevention and treatment of common lesions still require unification of criteria. Patients with haemophilia seek medical consultation exclusively for two reasons: because they have requested an appointment for a routine check-up (1-2 times a year in case of severe haemophilia) or because they have developed acute bleeding that requires treatment. The purpose of this paper is to emphasize the importance of an early differential diagnosis of joint damage and to review the techniques that allow an effective evaluation. The World Federation of Haemophilia recommends the 'Primary Prophylaxis' treatment modality, and today, severe haemophilia patients adhering to that factor VIII/IX therapy have significantly reduced common injuries: haematomas, haemarthrosis, synovitis, and haemophilic arthropathy. The basic protocols and minimum data for the control of musculoskeletal health are described. In summary, the primary goal of the haematologist-led multidisciplinary care team treating patients with haemophilia is likely to restore and/or preserve joint and musculoskeletal health, which is essential to promoting quality of life. Appropriate factor replacement regimens are required to prevent bleeding, these should be combined with physical activity and a physiotherapy program, in accordance with the recommendations of the World Health Organization for the general population.

Next generation sequencing in bleeding disorders: two novel variants in the F5 gene (Valencia-1 and Valencia-2) associated with mild factor V deficiency.

Inherited bleeding coagulation disorders (IBCDs) have a powerful diagnostic tool in next generation sequencing (NGS) that not only offers confirmation of diagnosis but also aids in genetic counselling, prenatal diagnosis and helps to predict the clinical course and follow-up of a disease. In our group, targeted-NGS using a Custom SureSelect QXT Panel (Agilent Technologies, Inc., Santa Clara, CA, USA) was designed to screen for causal variants in 40 genes related with the coagulation cascade. In this work, we used NGS for screening all the coding and intronic boundary regions of F5 gene in two patients affected by factor V (FV) deficiency (parahemophilia). Two new mutations were found: c.4745A>G (p.Tyr1582Cys, NM_000130.4) and c.1999_2002dupAATT (p.Ser668ter; NM_000130.4), both located in exon 13 of the F5 gene. We designated them Valencia-1 and Valencia-2 respectively. Valencia-1 could provoke loss of the fifth cupredoxin domain of the FV, and would be responsible for its defective activity. Valencia-2 prematurely stops the translation of mRNA, resulting in a truncated FV protein which lacks completely the B domain and the light chain. NGS has permitted to describe an increasing number of FV deficiency-causing mutations and a better understanding of FV's structure and function. The description of deficiency-causing mutations will continue to increase our knowledge of the functional residues of FV, as well as those which are involved in the correct folding of the protein. In this sense, NGS is a useful tool for studying IBCDs, as permits studying the whole coagulation cascade at once and gives a global view of the patient's genetic background.

Bayesian pharmacokinetic-guided prophylaxis with recombinant factor VIII in severe or moderate haemophilia A.

INTRODUCTION: Personalised pharmacokinetics (PK) using Bayesian analysis with limited sampling is assumed to help to optimise prophylaxis in haemophilia A (HA) patients. MATERIALS AND METHODS: Our prospective, observational study analysed the influence of PK parameters on clinical variables (bleeding rates, joint status, adherence, and consumption) using myPKFiT® in a cohort of twenty-one severe and moderate HA patients on prophylaxis with recombinant FVIII (Advate®) in two periods of one year, the first before PK-based tailoring and the second after PK-guided prophylaxis. Intra-individual and inter-individual coefficients of variation (CV) of half-life (t1/2) were calculated. RESULTS: A total of 73 PK estimations were performed in both periods, resulting in 17.2% inter-individual CV in mean t1/2, and 4.9% intra-individual CV. Before PK-based tailoring a significant association between joint bleeds and t1/2 was found (P = 0.010), especially in patients with short t1/2. This finding was reproduced (P = 0.013) after withdrawal of two patients with bleeding phenotype related to their advanced arthropathy but normal t1/2 and trough levels. Patients with joint bleeds weighed less (P = 0.039) and required higher doses (P = 0.032) than patients with zero joint bleeds. These associations were not observed in the second period after the adoption of PK-guided prophylaxis. There were no differences between the two periods, although a tendency to fewer spontaneous bleeds was suggested after PK-based tailoring. CONCLUSIONS: PK-guided prophylaxis facilitates an adequate level of bleeding control in patients with HA, maintaining clinical variables and patient convenience in an integrative manner, without increasing FVIII consumption.

Pilot evaluation of home delivery programme in haemophilia.

WHAT IS KNOWN AND OBJECTIVES: Most of the clotting factor (CF) dispensations to haemophiliac patients are centralized in a few haemophilia treatment centres, necessitating frequent visits and long travel distances. The aim was to evaluate the home delivery programme developed by the Outpatient Pharmaceutical Care Unit (OPCU) through the association of patients (ASHECOVA). METHODS: A specific software programme was designed to communicate the individual CF requirements. Dispensations were prepared in advance, and an ASHECOVA member collected and delivered to patients' homes in optimal conditions. Data regarding the programme were analysed from December 2011 to December 2017. An electronic satisfaction survey with 34 questions was conducted, asking about organizational aspects, education and communication, use of apps and satisfaction level. RESULTS AND DISCUSSION: Forty-nine patients were included and 2464 home deliveries were made, without any reported incident related to dispensation errors, drug preservation, communication or confidentiality problems. This system avoids 11.4 annual dispensation visits per patient to OCPU, and a mean travel distance, time and cost of 1189.1 km, 945.3 minutes and 373.5 euros, respectively. Overall satisfaction with home delivery was 9.7, without any change suggested in the current system. Ninety-five per cent of individuals believed that the programme improves adherence and all patients would recommend it to other patients. The most common benefits reported were less frequent visits to hospital, reducing time and cost spent on transportation. WHAT IS NEW AND CONCLUSION: The home delivery programme guarantees a proper follow-up of treatments with full patient satisfaction. This programme allows OPCU to achieve better pharmaceutical care, traceability of the process and optimization of working times and CF stock management.

Effect of radiosynoviorthesis on the progression of arthropathy and haemarthrosis reduction in haemophilic patients.

INTRODUCTION: Repeated haemarthrosis is widely accepted as the triggering cause of synovitis and haemophilic arthropathy. A first-line treatment of chronic synovitis is radiosynoviorthesis (RS). The aim of this study was to evaluate the RS effects on the progression of arthropathy and on a reduction in bleeding in patients with haemophilia. METHODS: An observational-retrospective study was performed. Bleeding episodes in the 12 months following and in the 12 months preceding RS was compared. The arthropathy was clinically and radiologically analysed by age range, joint and subject, comparing those undergoing RS (Radiosynoviorthesis Group, RSG) against those not undergoing this treatment (Non-Radiosynoviorthesis Group, Non-RSG). RESULTS: One hundred and seventy-four RS were performed in 71 patients (90 Y in Knees and 186 Re in elbows/ankles/shoulder). RS resulted in significant reduction in bleeding (582 preintervention and 168 postintervention, P < .001). In general, the level of arthropathy measured clinically and radiologically was greater with age increase in both groups (RSG and Non-RSG), especially in the 25-40 age range. A significant increase (P < .05) in the progression of arthropathy was also observed, both globally by patient and specifically for each joint, in non-RSG and RSG group. CONCLUSION: RS is an effective method to reduce the number of haemarthrosis episodes in chronic synovitis. Moreover, RS can positively affect arthropathy by slowing down its progression. However, the results obtained suggest that arthropathy may be conditioned by the subject's age, regardless of whether or not the joint has undergone RS.

HaemoPREF: Further evaluation of patient perception and preference for treatment in a real world setting.

INTRODUCTION: Adherence to haemophilia A (HA) treatment may be influenced by patients' beliefs about their condition and treatment. Furthermore, difficulties administering treatment may lead to poor adherence. New treatment strategies aim to reduce the burden associated with administration and to improve patient perception of treatment, which, in turn, increase adherence levels. AIMS: This study aimed to examine patient perception of HA treatment and related factors using patient-reported outcome (PRO) questionnaires and to confirm the psychometric properties of a recently developed questionnaire, the HaemoPREF. METHODS: A non-interventional, cross-sectional, questionnaire study was conducted with adult HA patients in Spain (n=31), Germany (n=10) and Italy (n=48), who were using ReFacto AF with the FuseNGo administration device. Patients completed the HaemoPREF and other questionnaires measuring related constructs: treatment adherence, satisfaction and well-being, online at two time points. Correlational, regression and psychometric analyses were conducted. RESULTS: PRO scores indicated that patients are satisfied with and adherent to their treatment. Multivariate regression of the HaemoPREF global score identified a number of significant predictors (P≤.05). The HaemoPREF Global Score had a moderate relationship with subscales on the related questionnaires (mean correlation=0.43; range=0.39-0.48). The HaemoPREF demonstrated good test-retest reliability (intraclass correlation coefficient=0.82), internal consistency reliability (Cronbach's alpha range=0.69-0.82) and convergent validity with measures of treatment satisfaction (Spearman correlation coefficient, r=.48) and well-being (r=.41). CONCLUSION: The findings suggest that patients using ReFacto AF with FuseNGo were satisfied with and adherent to their treatment. The HaemoPREF can identify important concepts relating to patient treatment experience in HA.

Development and psychometric validation of a brief comprehensive health status assessment scale in older patients with hematological malignancies: The GAH Scale.

OBJECTIVES: The purpose of this study was to develop a new brief, comprehensive geriatric assessment scale for older patients diagnosed with different hematological malignancies, the Geriatric Assessment in Hematology (GAH scale), and to determine its psychometric properties. MATERIALS AND METHODS: The 30-item GAH scale was designed through a multi-step process to cover 8 relevant dimensions. This is an observational study conducted in 363 patients aged≥65years, newly diagnosed with different hematological malignancies (myelodysplasic syndrome/acute myeloblastic leukemia, multiple myeloma, or chronic lymphocytic leukemia), and treatment-naïve. The scale psychometric validation process included the analyses of feasibility, floor and ceiling effect, validity and reliability criteria. RESULTS: Mean time taken to complete the GAH scale was 11.9±4.7min that improved through a learning-curve effect. Almost 90% of patients completed all items, and no floor or ceiling effects were identified. Criterion validity was supported by reasonable correlations between the GAH scale dimensions and three contrast variables (global health visual analogue scale, ECOG and Karnofsky), except for comorbidities. Factor analysis (supported by the scree plot) revealed nine factors that explained almost 60% of the total variance. Moderate internal consistency reliability was found (Cronbach's α: 0.610), and test-retest was excellent (ICC coefficients, 0.695-0.928). CONCLUSION: Our study suggests that the GAH scale is a valid, internally reliable and a consistent tool to assess health status in older patients with different hematological malignancies. Future large studies should confirm whether the GAH scale may be a tool to improve clinical decision-making in older patients with hematological malignancies.

Adherence to prophylaxis and quality of life in children and adolescents with severe haemophilia A.

Treatment adherence in adolescents with chronic diseases is around 50%, and failure is more common in preventive therapy. In haemophilia, contradictory results are reported by the published studies. The objective of this study was to evaluate adherence with factor VIII (FVIII) prophylaxis in Spanish patients with severe haemophilia A between age 6 and 20 years. Data were collected retrosp-ectively in the previous 2 years. The primary endpoint was the absolute adherence index (AAI), and the endpoints were related to clinical status, age, prophylaxis regimen, responsibility for factor administration and quality of life (QoL), assessed by the Haemo-QoL questionnaires. A total of 78 patients from 14 Spanish hospitals were recruited. Adherence ranged between -64.4 and 66.7 (mean -3.08). No differences were observed between children and adolescents (7.11 vs. 6.39; P = 0.809). A statistically significant association (P < 0.010) between infra adherent group and target joint was found, as was a statistically significant difference (P < 0.010) between the number of bleeding episodes experienced by the adherent group (mean 1.4) and by infra adherents (mean 4.5). There was no significant difference between AAI and prophylactic regimen (6.35 vs. 6.96, P = 0.848), neither between AAI and the person responsible for factor administration (5.57 vs. 8.79, P = 0.326). The Haemo-QoL scores (8-12 years) were related to adherence level (P < 0.05). Adherence was approximately ideal and patients perceived a high QoL. Because of the repercussions for compliance, it is essential to work during puberty on emotional and self-acceptance aspects of the disease, as well as coping, and the patient's family, school and health team relationships.

Novel investigations on the protective role of the FVIII/VWF complex in inhibitor development.

Development of inhibitory antibodies to infused factor VIII (FVIII) concentrates is the most serious unresolved complication of haemophilia A treatment. Systematic reviews suggest a twofold higher incidence of inhibitors with recombinant (rFVIII) vs. plasma-derived (pdFVIII) FVIII products, but study methodologies vary widely. The lower immunogenicity of pdFVIII concentrates is believed to derive from the presence of von Willebrand factor (VWF) which acts as protector and chaperone for FVIII. Several novel investigations reinforce the protective role of the VWF/FVIII complex in inhibitor development. At the basic science level, numerous in vitro and in vivo experiments have demonstrated that VWF-containing pdFVIII concentrates (pdFVIII/VWF) provide better protection against inhibitor neutralization than rFVIII products. Conformational aspects of the binding between VWF and FVIII are thought to prevent the 'attack' on FVIII by inhibitory antibodies. VWF/FVIII binding is 100% in pdFVIII products but only 80% in recombinant products and this 'free' FVIII may be a target for inhibitory antibodies. At the clinical level, newer strategies to prevent inhibitor development in previously untreated patients with severe haemophilia are under investigation. The concept of early prophylaxis (before the onset of a bleed) is convincing from a theoretical point of view but requires further evaluation. The Study on Inhibitors in Plasma-Product Exposed Toddlers is specifically addressing the issue of relative immunogenicity between classes of FVIII product (recombinant vs. plasma-derived). Currently nearing its target enrolment of 300 patients, this international randomized controlled trial is expected to provide some definitive answers about this ever-present clinical dilemma.

Inhibitor development after switching of FVIII concentrate in multitransfused patients with severe haemophilia A.

Switching between different therapeutic FVIII concentrate types has been postulated as a possible cause of inhibitor development in patient with haemophilia A. In this single-centre, retrospective study, the incidence, titre and duration of inhibitor development in multitransfused patients, defined as patients with more than 150 exposure days (ED), were analysed from January 1970 to December 2007 in relation to ED and the number of switches between different products. Inhibitor titre was assessed by Bethesda assay (before 1998) or Nijmegen assay (after 1998). Medical records of 167 patients were screened, of which 97 patients met the inclusion criteria. Fourteen products of plasmatic origin (different purities) and five recombinant (three generations) were used. Nine patients (9%) developed inhibitors, all transient, low-titre (1.41 ± 0.54 BU) after 323 ± 287 ED in average. Seventeen patients had no product switches of which four patients (23%) developed inhibitors (97 ED in average), whereas 13 patients (77%) did not (ED: 230). Fifty patients switched between plasmatic products only (median: 10 changes) of which five patients (10%) developed inhibitors (ED: 503), whereas 45 patients did not (ED: 932). Five patients switched between recombinant products only (seven changes) of which no patient developed inhibitors (748 ED). Twenty-five patients switched between plasmatic and recombinant products (13 changes) of which no patient developed inhibitors (ED: 1654). No statistically significant differences between patient groups were observed. Neither the number of different FVIII products administered nor the switching of products influenced the incidence of inhibitor in multitransfused patients.

The degree of neutropenia has a prognostic impact in low risk myelodysplastic syndrome.

The severity of neutropenia in myelodysplastic syndrome (MDS) has not been completely studied. We analyzed the prognostic significance of severe neutropenia (neutrophils count <0.5×10(9)/L) at diagnosis in 1109 patients with de novo MDS and low/intermediate-1 IPSS included in the Spanish MDS Registry. Severe neutropenia was present at diagnosis in 48 of 1109 (4%). Patients with severe neutropenia were most strongly represented within the groups of refractory cytopenia with multilineage dysplasia (40%) and refractory anemia with excess of blast type 1 (29%). Severe neutropenia had negative effects on the low/intermediate-1 risk group. A significant difference in overall survival was observed between patients with severe neutropenia (28 months) and patients with a neutrophil count higher than 0.5×10(9)/L (66 months) (p<0.0001). Also, severe neutropenia predicted a significantly reduced on leukemia-free survival (p<0.0001). In the multivariate analysis, severe neutropenia retained its independent prognostic influence on overall survival [HR: 2.19, 95% CI (1.41-3.10), p<0.0001] and leukemia free survival [HR: 3.51, 95% CI (1.97-6.26), p<0.0001]. The degree of neutropenia should be considered as additional prognostic factor in low/intermediate-1 IPSS MDS.

Relationships between antithrombin activity, anticoagulant efficacy of heparin therapy and perioperative variables in patients undergoing cardiac surgery requiring cardiopulmonary bypass.

INTRODUCTION: A study on 149 cardiopulmonary bypass (CPB) patients was performed to elucidate possible relationships between antithrombin (AT) activity and a subject's clinical profile or surgery characteristics. METHODS: An initial dose (300 IU/kg) of heparin was administered before CPB. Additional boluses (100 IU/kg) were administered if the activated clotting time (ACT)≤460 s. AT activity and hematological parameters were determined preoperatively, during and after CPB, and at 12, 24, 36, and 48 hours post-intervention. RESULTS: 29.5% patients required an additional dose of heparin during CPB. Preoperative AT was 96.5 ± 13.9% in all but 4 patients. AT was significantly lower during CPB and upon leaving the operating room (59.7%-80.0%). A small, but significant, inverse correlation was observed between AT at the end of CPB and the patient's age, as well as between basal preoperative AT and total heparin administered. CONCLUSIONS: Patient's age could be a moderate indicator of AT activity drop and low preoperative AT activity could be a sign of reduced anticoagulant efficacy of heparin during CPB.

Modelo agregométrico aplicado al estudio de la estabilidad de los concentrados de plaquetas conservados en solución aditiva PAS-2 / Aggregometric model applied to the study of platelet concentrates stability preserved in additive solution PAS-2

La demanda creciente de concentrados de plaquetas (CP) ha impulsado el desarrollo de investigación dirigidas al estudio de sustancias sintéticas que puedan sustituir al plasma en el proceso de producción de los CP. Nuestro objetivo es establecer una metodología que nos permita llevar a cabo un prorama de calidad en los CP y estudiar la influencia del PAS-2 sobre la función plaquetar a lo largo de su almacenamiento. Este programa de calidad se basa en la medida de la reacción plaquetar sobre plaquetas de los CP resuspendidos en plasma fresco congelado de un donante y la utilización de colágeno, ionóforo de calcio y ADP más epinefrina a unas concentraciones de: 16,6 µg/ml, 20 µM y 3 µM más 20 µM, respectivamente. Los resultados de la agregación plaquetar fueron algo superiores en CP-P que en CP-PAS. Sin embargo, la actividad plaquetar al sexto día de almacenamiento se mantiene en los CP-PAS con colágeno e ionóforo de calcio y desciente discretamente en los CP-P cuando utilizamos colágeno y ADP más epinefrina. Estos resultados sugieren que el PAS-2 es un buen medio sintético para utilizarlo como conservante en los CP. Este estudio in vitro se complementará con otro en desarrollo sobre la valoración del rendimiento in vivo de los CP producidos con medios sintéticos (AU)

Influence of methylene blue photoinactivation treatment on coagulation factors from fresh frozen plasma, cryoprecipitates and cryosupernatants.

OBJECTIVE: To study the influence of virus photoinactivation with methylene blue (MB) on the coagulation factors of fresh frozen plasma (FFP) and the corresponding cryoprecipitates and cryosupernatants derived from it. MATERIALS AND METHODS: The photoinactivation procedure of the German Red Cross (Springe) was applied using Biomat (Grifols, Spain). Twenty isogroup pools of three plasma units were made from 60 U of FFP. The pools were split into three bags. One of them was photoinactivated, and pre- and postinactivation samples (MB-plasma) were obtained. The second bag was treated in the same way, followed by the preparation of MB-cryoprecipitate and MB-cryosupernatant. The third bag was not photoinactivated, and was processed in the same way to obtain control cryoprecipitate and cryosupernatant. The prothrombin time and activated partial thromboplastin time were analysed, as well as fibrinogen, factors (F) II, V, VII, VIII, IX, XI and XIII, antithrombin III, von Willebrand (vW) F:RCo, vWF:Ag and the multimeric structure of vWF. RESULTS: In plasma, the proteins most sensitive to photoinactivation were fibrinogen, FV, FVIII, FIX and FXI (24, 32, 28, 23 and 27% loss, respectively). In the MB-cryoprecipitate, the losses were higher for FVIII (23%), moderate for fibrinogen, FXIII and vWF:RCo (18, 14 and 13%, respectively) and minimal (only 3%) for vWF:Ag. In MB-cryosupernatants, the losses were higher for FV (26%) and moderate for fibrinogen (16%), FIX (18%) and FXI (19%), as well as for FII and FXIII (15%). The multimeric structure of vWF was not modified in MB-plasma or in MB-cryoprecipitates. The supernatants (both MB treated as well as controls) showed an absence of multimers of very high and high molecular weight. CONCLUSIONS: The quantitative and qualitative conservation of coagulation factors achieved in MB-plasma-derived products suggest that they are useful for the global replacement of coagulation factors and for deficiencies in FV and FXI. In countries lacking the economic resources to obtain virally inactivated concentrates, MB-cryoprecipitates could be useful in von Willebrand's disease and fibrinogen and FXIII deficiencies. MB-cryosupernatants could be employed in thrombotic thrombocytopenic purpura, in the correction of total or partial deficiencies of prothrombin complex factors and in specific deficiencies of FV and FXI.

Quality analysis of blood components obtained by automated buffy-coat layer removal with a top & bottom system (Optipress (R)II).

BACKGROUND AND OBJECTIVE: There are Council of Europe recommendations for the quality of blood components. We analyzed the quality of blood components processed by a top & bottom system (Optipress((R)) II), the routine method used in our blood bank, to test whether the components reached the recommended quality. DESIGN AND METHODS: Blood was collected in triple CPD-SAGM bags (Optipac((R)) Baxter). Whole blood (WB) was centrifuged at 4,158 g for 14 min before separation by an automated top & bottom system (Optipress((R) )II). Platelet concentrate (PC) was prepared by pooling four isogroup buffy-coat (BC) units before low-speed centrifugation, and transferring the supernatant (4 BC-PC) to a 5-day storage bag (PL732, Baxter). An alternative approach involved PC preparation from a single BC unit by adding approximately 70 mL of plasma before centrifugation, followed by transfer of the platelet concentrate (1BC-PC) to a 300 mL Teruflex((R)) transfer bag. Both 4 BC-PC and 1 BC-PC were stored in a flat agitator at 22 degrees C for up to 5 days after collection. Cell counts were determined, along with hemoglobin and hematocrit in a Sysmex K-800 cell counter. The pH was determined on day 5 at 22 degrees C. Weights were measured and volumes were calculated based on specific gravity. Statistical analyses were carried out using the Kolmogorov-Smirnov test as a normality distribution test, the t-test for parametric values and Wilcoxon's test as a non-parametric test. Statistical significance between samples was considered to have been reached when p<0.05. RESULTS: The best parameters for configuring the system were: strength 25; BC volume 33-55; level of BC 5.5. Red blood cell (n = 1,434) volume was 279+/-20 mL, with 54.92+/-7.16 g of hemoglobin. More than 96% of units had fewer than 1.2x10(9) white blood cells. Fresh plasma volume (n = 803) averaged 279+/-19 mL, with a white blood cell contamination of fewer than 0.1x10(9)/L in all samples examined (n = 23). Platelet recovery in BC was 92+/-9% of platelets present in WB; the percentage of removed leukocytes was 74+/-10%, and between 13 and 15% of RBCs were lost in the BC (95% confidence interval). The BC volume (n = 1,037) fitted the target volume of 60 mL, except for some devices, when Optipress II((R)) lost the configuration for this parameter. Of 4 BC-PCs 80.3% yielded more than 0.6x10(11) platelets per unit, whereas this criterion was only met by 59.7% of 1 BC-PCs, and a greater proportion of 1 BC-PCs (58.8%) showed pH values within the range of 6.5-7.4 after 5 days of storage in comparison with 4 BC-PCs (44.25%). INTERPRETATION AND CONCLUSIONS: Optipress II((R)) provides standardized, leukocyte-poor blood components. Council of Europe requirements were met in a large percentage of red-cell concentrates, with less than 92 and 74% of the original platelets and leukocytes, respectively, and a small hemoglobin loss per unit. The system gave an optimal yield in terms of plasma volume. The top & bottom technique allowed us to reduce the number of blood units per platelet concentrate from 6 to 4 units, with similar platelet yields compared with traditional procedures. Nevertheless, the storage conditions must be improved to satisfy all Council of Europe requirements for platelet concentrates.

A new method for phenotyping red blood cells using microplates.

BACKGROUND AND OBJECTIVES: The supply of phenotyped red blood cells (RBC) for patients with several RBC antibodies presents a difficult task to hospital blood banks and regional blood centers. The aim of this study was to establish a low-cost typing system to allow extensive phenotyping of regular blood donors for clinically significant RBC antigens. MATERIALS AND METHODS: We developed a new buffer that greatly intensifies the antigen-antibody reaction and thus reduces the quantity of serum needed for phenotyping. The procedure was carried out on microplates. RESULTS: A total of 20,435 regular blood donors have been typed to date. For 752 units required for transfusion, 3,584 phenotyping tests were performed, validating the results by tube or gel typing methods; agreement was achieved in all cases. CONCLUSION: This technique seems adequate for phenotyping a large number of RBC units at very low cost, thus facilitating the availability of phenotyped blood.