Standardization and comparison of nonautomated assays to measure the collagen binding activity of von Willebrand factor.

INTRODUCTION: Diagnosis of von Willebrand disease (VWD) is difficult due to the heterogenic phenotype of patients and to the complex tests that are required for an adequate investigation. The collagen binding assay (VWF:CB) reveals the adhesion capacity of von Willebrand factor (VWF) to collagen and can be useful to reduce the misleading diagnosis of VWD. This study aimed the standardization of 2 nonautomated VWF:CB assays based on ELISA and flow cytometry. METHODS: Plasma samples from 87 patients previously diagnosed with VWD and 22 healthy controls were analyzed. Measurement of the VWF-collagen binding activity was performed using a commercial assay and the 2 tests proposed. VWF:CB/VWF:Ag ratio was calculated for samples and the differentiation between types 1, 2A, and 2M was analyzed. RESULTS: ELISA and flow cytometry tests presented strong correlation with the gold standard test (r2  = .8976 and r2  = .8143, respectively). Tests based on ELISA and flow cytometry presented a bias of +7.2% and -3.6%, respectively. CONCLUSION: The ELISA test demonstrated better performance to detect VWF-collagen binding activity in healthy individuals and VWD patients. This test could differentiate 2A and 2M subtypes using a feasible protocol that can be easily implemented.

Effect of red blood cell preservation by droplet freezing with non-permeable cryoprotective agents in blood group antigen reactivity.

BACKGROUND: In the last few decades, various red blood cell (RBC) freezing techniques have been developed and improved to enable the preservation of erythrocytes for future use in pre-transfusion tests in reference immunohaematology laboratories. However, not all these techniques have been sufficiently evaluated for the preservation of blood group antigens. OBJECTIVES: In this study, we evaluated the antigenic pattern of RBCs preserved by droplet freezing in liquid nitrogen in a blood bank context. METHODS: Blood samples were evaluated for the reactivity of blood group antigens after droplet freezing using the non-permeable cryoprotective agent polyvinylpyrrolidone (PVP) and sucrose-dextrose (S + D) solutions. RESULTS: No qualitative changes were observed in RBC reactivity after freezing and thawing for the antigens Fyb , Leb , C, E, Cw , Lua , Lub , Kpa , Kpb and Dia . However, cryopreservation using PVP resulted in a significant increase in reactivity of Fyb antigen on comparing fresh and frozen samples (P < 0·001). CONCLUSION: The establishment of detailed protocols for cryopreservation of RBCs, which take into account the maintenance of antigenic characteristics, is necessary to increase security in pre-transfusion testing using frozen RBCs.

Determining the health-related quality of life in individuals with haemophilia in developing economies: results from the Brazilian population.

INTRODUCTION: Several studies show the negative impact of haemophilia in health-related quality of life (HRQOL). This issue is not well explored in developing countries. OBJECTIVES: This cross-sectional study aimed to evaluate the HRQOL and its associated factors in patients with haemophilia A/B in Brazil. Data were collected by questionnaire and in medical records, including a Portuguese version of Haem-A-Qol. RESULTS: Brazilian patients were invited to the study and 175 participants (147 haemophilics A and 28 haemophilics B) were included. The total score of the Haem-A-QoL had a median of 36.96 (range of 0-100), with worse performance in 'sport and leisure' and best on 'relationships' fields. HRQOL was worst among the older participants, the less educated, non-white, non-working, who were hospitalized in the last year, who did not have a single medical consultation and among those with the highest number of affected joints. Moreover, patients with hepatitis B had a significantly worse HRQOL in the domain 'sports and leisure', also observed in married patients. Otherwise, married individuals reported better HRQOL on 'dealing with the disease' domain. Patients with haemophilia B reported worse HRQOL in the domain 'self-perception'. CONCLUSION: The results obtained could be helpful in guidance of haemophilia treatment which is determinant to improve HRQoL of the most vulnerable groups of patients. This work also reinforced the relevance of joint bleeds in all aspects of HRQoL in haemophilic patients. The use of prophylactic factor concentrates and multidisciplinary treatments could contribute to improve the quality of life in haemophilia.

Cytokine profile and FVIII inhibitors development in haemophilia A.

Haemophilia A is a hereditary bleeding disorder linked to the X chromosome characterized by a deficiency or defect in the coagulation factor VIII (FVIII). Individuals with this coagulopathy require constant infusions of FVIII to maintain their physical integrity and haemostasis. During treatment, some patients develop an immune response that produces antibodies to FVIII, also called inhibitors, affecting the pro-coagulant activity of this protein. Despite the clinical relevance of FVIII inhibitors, the immune mechanisms that lead to their production are not known. This study investigated the immunological cytokine profile using plasma from HA patients which were either positive or negative for FVIII inhibitors and from healthy individuals. The results showed that healthy individuals and HA patients that do not develop FVIII inhibitors have a mixed immune response profile with high secretion of IFN-γ, TNF-α IL-2 and IL-5. In contrast, HA patients with FVIII inhibitors exhibited an anti-inflammatory/regulatory immune response characterized by low levels of all measured cytokines except for IL-4 and IL-10. This profile may be related to the development and maintenance of the FVIII inhibitors. By comparing the cytokine profiles of the three different groups we have established a model explaining the immune activation resulting in the production of FVIII inhibitors in haemophilia A patients.

A shift towards a T cell cytokine deficiency along with an anti-inflammatory/regulatory microenvironment may enable the synthesis of anti-FVIII inhibitors in haemophilia A patients.

Despite the clinical relevance of anti-factor VIII (FVIII) antibodies (anti-FVIII inhibitors) impairing haemostatic activity of haemophilia A (HA) patients, the immunological mechanisms underlying their production are unknown. Aiming to understand more clearly the immune response in patients with [HAα-FVIII(+)] and without [HAα-FVIII(-)] anti-FVIII inhibitors, we have characterized the cytokine pattern of peripheral blood leucocytes, using an in vitro stimulation of whole blood samples with plasma-derived (pFVIII) or recombinant FVIII (rFVIII). The results highlighted decreased levels of tumour necrosis factor (TNF)-α(+) neutrophils with higher interleukin (IL)-5/TNF-α ratio in HAα-FVIII(+). All HA samples displayed decreased levels of IL-10(+) monocytes when compared to the blood donor (BD) samples. HAα-FVIII(+) showed lower levels of TNF-α(+) monocytes and increased IL-10/TNF-α ratio. Analysis of adaptive immunity revealed increased levels of interferon (IFN)-γ(+) , TNF-α(+) and IL-4(+) T-cells, from both CD4(+) and CD8(+) T cells, in HAα-FVIII(-) when compared to BD. Moreover, increased frequency of IL-10(+) B cells and higher levels of α-FVIII IgG1 were observed in HAα-FVIII(-). Basal levels of cytokine(+) B-cells, similar to BD, and higher levels of α-FVIII IgG4 are major features in HAα-FVIII(+). The global cytokine profile demonstrated a major anti-inflammatory/regulatory pattern in HAα-FVIII(+), confirmed by the in vitro stimuli with pFVIII or rFVIII. The polarized anti-inflammatory/regulatory immune response in HAα-FVIII(+) and the mixed pattern with a bias towards an inflammatory cytokine profile, modulated by IL-4 in HAα-FVIII(-), may be the key element to drive the development of distinct subclasses of anti-FVIII antibodies. These finding have implications for the design of safe and effective therapeutic protocols to control inhibitors synthesis in HA patients.

Reactivity profile of anti-factor VIII antibodies with designed synthetic peptides mimicking epitopes of the C2 and a1 domains.

Antibodies (Abs) that block factor VIII (FVIII) activity occur in hemophilia A patients treated with FVIII replacement therapy and severely impair treatment. In this work, we designed and synthesized ten peptides whose sequences are found in putative epitopes at the surface of a1 and C2 domains of the FVIII molecule. These peptides were screened for their ability to inhibit the binding of anti-FVIII Abs from plasmas of hemophilia A patients to FVIII. All peptides were efficient in inhibiting anti-FVIII Abs in plasma from patients with inhibitors, with however different efficiencies. It was found that each tested patient's plasma had a different profile of reactivity with peptides, consistent with an individual anti-FVIII Ab specificity. The profile of recognized peptides was also changing during the treatment of the patients. Three peptides were used in an affinity chromatography assay to attempt to remove anti-FVIII Abs from patients' plasma. Anti-FVIII IgGs were significantly captured by the peptide-Sepharose affinity matrixes as assessed by enzyme-linked immunosorbent assay. However, due to the low level of Abs in the plasma samples, other methods (Chromogenic and Bethesda assays) were not sensitive enough to properly detect the reduction of inhibitors.