Hemophilia Group Research Articles

Factor VIIa analog has marked effects on platelet function and clot kinetics in blood from patients with hemophilia A

To evaluate the hemostatic effects of NN1731 and rFVIIa, an ex-vivo study in hemophilia patients used the Hemodyne Hemostasis Analysis System (HAS) to measure platelet contractile force (PCF), clot elastic modulus (CEM), and force onset time (FOT), and the Haemoscope Thrombelastograph (TEG) to measure reaction time (R), kinetics time (K), and maximum amplitude (MA). Blood samples from 10 healthy volunteers and 10 Factor VIII-deficient patients of varying severity (mild, moderate, severe), were spiked with rFVIIa and NN1731 (both 0.64 and 1.28 microg/ml, respectively) and analyzed to characterize platelet function and clot kinetics. There was wide variability in the rFVIIa response. NN1731 had greater and more consistent effects on PCF, CEM, FOT, R, and K relative to rFVIIa, in all hemophilia groups. The lowest NN1731 concentration (0.64 microg/ml) shortened R and FOT, and increased CEM and PCF more than rFVIIa 1.28 microg/ml. NN1731 normalized clotting parameters equivalent to values obtained in healthy volunteers. FOT and R were highly correlated (r = 0.96). No correlation was observed between CEM and MA. NN1731 produced less variable, more pronounced and predictable ex-vivo hemostatic effects on PCF, CEM, FOT, R and K than rFVIIa in all hemophilia groups. HAS and TEG assays provided similar estimates of FOT and R, however CEM appeared to be more sensitive than MA to changes in clot firmness.

Analysis of cytokine genes polymorphism as markers for inhibitor development in haemophilia A

Antibodies that block factor VIII (FVIII) activity appear in some haemophilia A patients treated with FVIII replacement therapy and severely impaired treatment. To date, the mechanisms that lead to this immune response are unknown. In this work, haplotypes of cytokine interleukin 10 (IL-10) gene have been associated with the presence of FVIII inhibitors in a group of Brazilian haemophilia A patients. The coexistence of a haplotype defining high IL-10 synthesis and one defining an intermediate production of cytokines is found to be associated with the group of patients who have a history of inhibitor development. Additionally, the coexistence of haplotypes defining high and low IL-10 syntheses is strongly associated with the group of negative inhibitors. These results have shown that the simple association considering only the presence or the absence of a haplotype and the development of inhibitors in haemophilia A is not sufficient. Data obtained in this work sustain the idea that the genetic studies may partly explain why only approximately 25% of haemophilia A patients develop FVIII inhibitors. Other genetic issues and details of the protein replacement therapy should be considered to measure the chances of a patient to develop anti-FVIII antibodies.

Thromboelastography reflects global hemostatic variation among severe haemophilia A dogs at rest and following acute exercise

The heterogeneity among severe haemophilia A patients reflects on variable tendencies for bleeding and also variable responses to FVIII therapy. This variability cannot be detected or predicted by routine coagulation tests. Thromboelastography (TEG) has recently been evaluated for assessing hemostatic patterns in haemophiliacs and proved valuable in monitoring therapy and/or prophylaxis, however, usually only in limited small case series. Exercise is an important component of overall haemophilia care, however, in severe haemophiliacs there is an increased risk of bleeding. The availability of a validated hemostatic test to evaluate the influence of exercise would be advantageous. This study has used TEG analysis to evaluate the global hemostatic status of a group of severe haemophilia A dogs at rest and after a standardized period of exercise. The study demonstrated significant inter and intra-individual variations based on TEG patterns at rest and following acute exercise as well as significant improvement of global hemostasis after exercise in the majority of tested dogs. The study supports the utilization of TEG in assessment of the hemostatic pattern in severe haemophilia A and provides a potential for utilizing TEG evaluation in managing exercise regimens for haemophilia care.

Inattention, hyperactivity‐impulsivity, academic skills and psychopathology in boys with and without haemophilia

The aim of this study was to determine if symptoms of inattention (IN) and hyperactivity-impulsivity (HI) differ for boys with and without haemophilia and to determine if IN and HI are the essential behavioural dimensions on which the two groups differ. Using a quasi-experimental design, parents' and teachers' ratings of IN and HI for boys with and without haemophilia (ages 6-14 years) were compared. IN and HI were also assessed with a psychometric task, as were reading and math, psychopathology, and educational status via various techniques. Boys with haemophilia (n = 19) were rated higher on dimensions of HI and IN by teachers (P = 0.01, P = 0.02, respectively) but only on HI by parents (P = 0.01). In addition, the haemophilia group committed more impulsivity errors on a psychometric task (P = 0.01). Trends, but not statistically significant differences, were found on reading and math scores, and the haemophilia group had more special education participation. Compared to national norms, borderline range scores on the attention-deficit/hyperactivity disorder (ADHD)-related dimensions of HI and psychometrically measured impulsivity characterized the boys with haemophilia. Although not addressing formal diagnoses, this study found that boys with haemophilia risk ADHD-spectrum problems, especially HI, and special education participation, but not frank academic deficits.

Oral and general health‐related quality of life among young patients with haemophilia

The clinical diagnosis of dental diseases may indicate their cause and prognosis, however it gives little information about resulting levels of impairment from the patients' perspective. In this study, we aimed to investigate oral and general health-related quality of life (OHRQoL-HRQoL) in patients with haemophilia; and to test whether haemophiliacs would have worse or better OHRQoL compared with the general population. Data were collected from haemophiliacs (age range 14-35; mean 23 +/- 6.58, n = 71) and age/sex-matched controls (age range 14-35; mean 21.00 +/- 6.45, n = 60) through face-to-face interviews including nine questions and using oral health impact profile (OHIP)-14, oral health-related quality of life-UK (OHQoL-UK), short-form general measure of health (SF)-36 to measure self-rating oral health status, perceived dental treatment needs, tooth brushing frequencies, OHRQoL-HRQoL. In the field of self-rating oral health status, perceived dental treatment needs, tooth brushing frequencies and OHIP, OHQoL-UK, SF-36 scores - except the subscales including vitality, role emotional and mental health - the control group is in better conditions compared with the haemophilia group. At the same time, both the two groups are in good conditions in dental attendance, vitality, role emotional and mental health. Life quality is related with the perceived discrepancy between the reality of what a person has and the concept of what that person wants, needs or expects. In order to eliminate the dilemma in the field of health, we should facilitate the haemophiliacs' lives by serving the health care in a multidisciplinary view.

Six-minute walk test in children with chronic conditions

ObjectivesThe 6-minute walk test (6MWT) is a frequently used indicator of functional exercise capacity. The goals of this study were to compare the 6-minute walk performance of three paediatric patient...

Comparison of Quality of Life across Adolescents with Cancer, Sickle Cell Disease and Hemophilia.

The purpose of this study is to assess Quality of Life (AQoL) of adolescents with cancer and compare it to adolescents with other hematological disorders who receive medical care from the Hematology/Oncology Clinic at Children's Mercy Hospitals and Clinics (CMHC). Children with cancer are surviving longer due to improved medical care, and cancer is recently being recognized as a chronic illness. The other two disease conditions we are comparing the QoL of adolescents with cancer are - sickle cell disease (SCD) and hemophilia. Literature shows evidence that for each disease condition, patients have lower QoL compared to their healthy counter-parts, but there is a void in area of research comparing QoL of adolescents with cancer to other blood diseases like hemophilia and SCD. This project was funded by Children's Mercy Cancer Center Board.Methods - Subjects between ages of 11 to 17 years with diagnosis of cancer, sickle cell disease or hemophilia that are followed at CMHC were eligible to participate. We mailed out AQoL questionnaires to 100 oncology, 100 sickle cell, and 52 hemophilia adolescents who were identified from database. Data was collected using a Likert-scaled instrument with 25 questions under four major sub-domains - Physical, emotional, social and functional well being. The AQOL scores for each domain represented an average of the Likert scale items with a theoretical minimum of 0 and a theoretical maximum of 4. We defined a difference of 0.5 or greater on any subdomain as having clinical relevance.Results 41 oncology, 29 SCD and 17 hemophilia responses were received back. Demographic data were self-disclosed to describe the sample population. Overall AQoL scores ranged from 0.0 to 4.0 for Phys, 1.0 to 4.0 for Soc, 0.4 to 4.0 for Emotional, and 1.4 to 4.0 for Functional subdomain. For all four measures, the scores were skewed right (clustered towards the upper limit with a long tail extending to the lower values). Only the Physical subdomain showed a borderline effect (p=0.056) with the Hemophilia group showing a larger mean than the other two groups. The remaining subdomains did not exhibit differences large enough to be clinically or statistically significant. Although there were small difference in the Oncology group with gender on the Physical and Emotional scale, these difference were not statistical significant. The differences on the Social and Functional well being scale were very small and within the range of clinical indifference, even after allowing for sampling error. There were no statistical or clinical differences in the Sickle Cell group between boys and girls, but this may be due to the small sample size in this group. No comparison with gender was possible in the hemophilia group. There were no statistical differences in the oncology group between those on or off treatment, but this may also be due to the small sizes in these groups.Conclusion With a few exceptions, the QOL subdomains showed no statistically significant or clinically significant differences between the three disease groups or between the boys and girls within each disease groups. This may be due, in part, to the small sample size of this study. There were two trends with achieved borderline significance: hemophilia patients showed higher AQOL scores on the physical and emotional subdomains.

Force fluctuations during the Maximum Isometric Voluntary Contraction of the quadriceps femoris in haemophilic patients

In the general population, the degenerative processes in joints are directly related to adult age, and osteoarthrosis represents the most frequent musculoskeletal alteration. In the haemophilic patient, the degenerative processes in the joint begin at very early ages, and are directly related to musculoskeletal bleeding episodes, which are occasionally subclinical and constitute haemophilic arthropathy. In the haemophilic patient, arthropathy constitutes the most frequent, severe and disabling pathology, and its assessment includes muscular force-related parameters. We have studied the value of Maximum Isometric Voluntary Contraction in the quadriceps femoris of 46 subjects, 28 haemophiliacs (16 severe, eight moderate and four mild) and 18 healthy individuals with a view to establishing appropriate values of force and to restoring physical therapy recommendations. The maximum force values were significantly greater (P < 0.001) in the healthy individuals group. The mild haemophiliacs group also presented significant differences of force (P < 0.05) in relation to the severe and moderate haemophilic patient groups. The mild and severe haemophilia patients presented greater fluctuations of force (P < 0.001) than the control group, the haemophilia group have a minor skill to produce constant force. The seriousness of the arthropathy in the knee is directly related to diminished values of maximum force. Our work evidences that patients with severe haemophilia present a greater degree of arthropathy in relation to moderate and mild haemophilia patients. Haemophilic arthropathy is associated with muscular atrophy and strength deficit. In haemophilic patients, the deficit of maximum force and the presence of fluctuations may suggest an increased risk of bleeding during physical activities and the need to programme specific physical therapy guidelines which increase muscular power through resistance training.

The tragic history of AIDS in the hemophilia population, 1982-1984.

The tragic history of AIDS in the hemophilia population, 1982-1984.

856. Improvements on Safety and Efficacy of Nonviral Gene Therapy of Factor VII for Hemophilia A with Inhibitors

Recombinant activated factor VII (rFVIIa) has been used as an effective alternative treatment for hemophilia patients who have developed inhibitors. We have successfully modeled a nonviral gene therapy approach to deliver factor VII (FVII) in a hemophilia A mouse model to decrease the cost and frequency of rFVIIa infusions. An engineered murine FVII (mFVIIa) cDNA was inserted into our gene transfer vector to generate a liver_specific construct pBS_ HCRHPI_mFVIIa_A encoding a modified protein, which can be cleaved by intracellular proteases of the furin family to secrete the activated form of mFVII. Partial correction of bleeding was achieved following nonviral gene transfer of this construct into hemophilia A mice. To increase the safety and efficacy of FVII gene therapy, we devised two approaches. The first was to use a mFVII wild_type cDNA (mFVII) encoding the zymogen FVII to reduce the potential thrombotic risk associated with prolonged, high level FVIIa expression. The second was to use a mutant FVIIa or FVII molecule (mFVIIa_DVQ or mFVII_DVQ) encoding a superactive FVII molecule with amino_acid substitutions (V158D/E296V/M298Q; Persson et al., 2003) to increase the efficacy of nonviral gene transfer of FVII. Fifty mg of the respective plasmids encoding wild_type or modified proteins including mFVII, mFVIIa, mFVII_DVQ, and mFVIIa_DVQ, were delivered into 4 groups of hemophilia A mice by a rapid, high volume (hydrodynamics_based) infusion method (n=8 mice/group). Phenotypic correction was measured via tail_clip assays. A 30% reduction in hemoglobin loss was observed in mice treated with mFVII, and a 50% reduction in mice treated with mFVIIa. Significant and long_term correction in PT using 1:60 dilution of mouse plasma was observed in both mFVII and mFVIIa treated mice, with clotting values consistently lower than wild_type and hemophilia A controls (wild_type: 26.4 s, hemophilia A: 25.4 s, mFVII: 23.6 s, mFVIIa: 23.3 s). APTT performed on plasma diluted 1:3 similarly reflects the results of the PT assay, with lowered clotting times for both groups of treated mice (wild_type: 60.2, hemophilia A: 121.3, mFVII: 102.8, mFVIIa: 100.9). Both plasma_ based and platelet_based thrombin generation (TG) assays indicated that both mFVII and mFVIIa have a positive effect on the three measured parameters with a lowered lag phase, lowered peak time and elevated peak thrombin levels. In addition, all these effects lasted long_term in plasmid treated mice for at least six months (experimental duration). Preliminary experiments using our most recently built constructs mFVII_DVQ and mFVIIa_DVQ showed reversion to wild_type phenotype in plasmid_treated mice as indicated by significantly reduced hemoglobin loss via tail clipping and substantial reduction in APTT. These results clearly demonstrate that nonviral gene therapy of either zymogen FVII or activated FVII can rescue bleeding in hemophilia A mice, and mFVII_DVQ/mFVIIa_ DVQ may potentially recover wild_type clotting activity in treated mice.

Severe Hemophilia and Physiologic Inhibitors of Coagulation

Patients with hemophilia demonstrate quite variable clinical phenotype even in cases with the same level of deficient factor or the same molecular abnormality. Different interacting factors including congenital and acquired alterations of coagulation inhibitors can modulate both clinical expression and severity of hemophilia. In this study, plasma levels of factor VIII (FVIII), factor IX (FIX) as well as protein C (PC), protein S (PS), and antithrombin (AT) plasma levels were measured in 80 patients with severe hemophilia A and B. Patients were divided into two groups according to the risk of bleeding: the first group (n = 32) with mild bleeding (< 2 bleeds/year), and the second group (n = 48) with severe bleeding (> or = 2 bleeds/year). Both hemophilia groups showed significantly decreased PC plasma levels compared to levels in healthy control subjects (the first group: p < 0.0001 and second group: p < 0.01). The difference in PC plasma levels between the first and second hemophilia group was significant (p < 0.05). Moreover, there was positive correlation between age and the functional PC in both hemophilia groups. Our results suggest that decreased PC plasma levels can testify to a slightly protective effect of the PC pathway on the severity and frequency of bleeding in patients with severe hemophilia A and B.

Dependence of Vector Dose and Age of Mice in the Induction of Immune Response Against Factor VIII Following Liver-Directed Nonviral Gene Transfer.

Formation of inhibitory antibodies to transgene product may limit the success of gene therapy especially for the treatment of hemophilia A. The risk of forming inhibitory antibodies against factor VIII depends on multiple factors. Previously we have shown that following naked gene transfer of fifty micrograms of a liver-specific, high-expressing factor VIII plasmid, pBS-HCRHPI-FVIIIA into hemophilia A mice (at least 60 days old), a robust humoral response was induced two weeks post plasmid injection despite of initial high-level gene expression of factor VIII (Ye et al. (2004) Mol. Ther. 10, 117–126). This response completely inhibited the activity of circulating factor VIII although factor VIII was persistently expressed in the liver. In this study, the cytokine production was characterized in human factor VIII-activated T cells from plasmid-treated and untreated hemophilic A mice, consistent with a response predominantly mediated by Th2-induced signals. Injection of plasmid DNA into 4 groups of hemophilia A mice (n=5, 60 days old) with 4 different doses (0.4, 2, 10, & 50 microgram per animal) resulted in vector dose-dependent expression of factor VIII. In addition, the two groups of mice with lower doses of plasmid DNA (0.4 & 2 microgram per animal) did not elicit any antibody response against factor VIII, whereas the two groups of mice with higher doses of plasmid DNA (10 & 50 microgram per animal) induced inhibitory antibody formation. Nevertheless, when the two groups of animals (n=4) with lower doses were treated with second injection of fifty microgram of factor VIII plasmid 180 days post plasmid delivery, all mice developed inhibitors suggesting no immune tolerance was induced by first injection of plasmids. Furthermore, fifty micrograms of factor VIII plasmids were injected into 4 groups of hemophilia A mice (n=5) of 4 different age groups (36, 48, 60 & 72 days). It was found that none of the mice with age 36 days at the time of plasmid injection developed inhibitors, 1/5 mice with age 48 days developed inhibitors, whereas the two groups of mice with age 60 & 72 days all developed high-titer inhibitors. These results indicate that induction of anti-factor VIII antibody following gene therapy is strongly dependent upon the vector dose and age of the animals, which has important implication for developing immunomodulation or other strategies to avoid/eliminate antibody responses.

Naked DNA Transfer of Factor VIII Induced Transgene-Specific, Species-Independent Immune Response in Hemophilia A Mice

The development of antibodies to a previously unexpressed protein product may limit the success of human gene therapy approaches. We inserted B-domain-deleted factor VIII (FVIII) cDNA of human, canine, or murine origin into the multiple cloning site of a liver-specific vector, pBS-HCRHPI-A, to yield plasmids pBS-HCRHPI-FVIIIA, pBS-HCRHPI-cFVIIIA, and pBS-HCRHPI-mFVIIIA, respectively. Fifty micrograms of each plasmid in 2 ml of solution was rapidly injected into the tail vein of three groups of hemophilia A mice. Factor VIII levels ranging from 3 to 12 IU/ml were obtained from all three groups (normal is 1 IU/ml in human plasma) 3 days after treatment. These initial very high levels of functional human, canine, or murine factor VIII, however, fell gradually to undetectable levels within 2–3 weeks, and their disappearance correlated with the generation of high-titer, inhibitory anti-FVIII antibodies. Notably, this immune response occurred independent of the species of origin of the exogenous factor VIII. Antibody titers to factor VIII were detected beginning at 2 weeks, reached a plateau and remained at high levels for over 6 months. The majority of anti-hFVIII IgG was IgG1 isotype specific, suggesting a humoral response mediated by Th2-induced signals. Consistent with this idea, in a separate group of mice treated with pBS-HCRHPI-FVIIIA, transient immunosuppression by cyclophosphamide significantly delayed (5/6) or abolished (1/6) inhibitory antibody formation against the transgene.

Does an enzyme other than thrombin contribute to unexpected changes in the levels of the different forms of thrombin activatable fibrinolysis inhibitor in patients with hemophilia A, hemophilia B and von Willebrand disease?

Pro-thrombin activatable fibrinolysis inhibitor (pro-TAFI), also called plasma procarboxypeptidase B or U, is one of the modulators of fibrinolysis in blood. Pro-TAFI is activated by thrombin/thrombomodulin complex or by plasmin to a carboxypeptidase B-like enzyme (TAFI) of 35.8 kD molecular weight. TAFI spontaneously becomes inactive as a result of a temperature-dependent conformational change in the protein (TAFIi). In this study, pro-TAFI, total TAFI antigen and TAFI-TAFIi antigen levels were measured in 32 patients with hemophilia A, 4 patients with hemophilia B, 21 patients with von Willebrand disease (VWD) and 13 healthy controls. A statistically significant decrease in pro-TAFI was found in all groups (10.72±4.57 mg/L (p<0.001); 8.00±2.35 mg/L (p<0.01) and 8.98±2.33 mg/L (p<0.001) for hemophilia A, hemophilia B and VWD, respectively) compared to controls (17.85±4.61 mg/L). A statistically significant increase in TAFI-TAFIi antigen was found in hemophilia A (1.05±1.01 mg/L) (p<0.05) and in VWD patients (0.96±1.01 mg/L) (p<0.05) compared to controls (0.55±0.36 mg/L). There was no difference in total TAFI antigen levels between any group of patients and the controls. Neither did pro-TAFI nor TAFI-TAFIi levels differ within the group of hemophilia A patients in relation to severity (mild, moderate and severe) or among the VWD patients in relation to subtype (type 1, type 2A and type 3). These findings indicate an increased conversion of pro-TAFI to TAFI and/or TAFIi in patients with bleeding disorders. As thrombin generation is seriously impaired in these patients and almost absent in hemophilia A and B and in type 3 VWD, it is possible that plasmin mediates pro-TAFI activation in these patients. Enhanced fibrinolysis via generation of plasmin has previously been reported in hemophilia and VWD. Activation of pro-TAFI by plasmin may be a feedback mechanism that counterbalances increased fibrinolysis in patients with bleeding disorders. The relationship between the TAFI activation pathway and bleeding complications associated with hemophilia A, hemophilia B and VWD requires further investigation.

Expression of therapeutic levels of factor VIII in hemophilia A mice using a novel adeno/adeno-associated hybrid virus.

We have generated an E1a/E1b/E3-deleted adeno/adeno-associated (Ad/AAV) hybrid virus driven by a small nuclear RNA (pHU1-1) promoter for expression of a B domain-deleted (Thr761-Asn1639) factor VIII transgene (FVIIIDelta761-1639). Productive replication of Ad/AAV/FVIIIDelta761-1639 in AAV rep-expressing cells resulted in generation of monomeric and dimeric mini-adenoviral (mAd) replicative forms that retained the AAV integration elements (mAd/FVIIIDelta761-1639). In vitro studies using Ad/AAV/FVIIIDelta761-1639 generated approximately 2-logs greater FVIII activity than mAd/FVIIIDelta761-1639. To determine its capacity for in vivo excision and/or genomic integration, Ad/AAV/FVIIIDelta761-1639 was injected by tail vein into three groups of hemophilia A mice (2 x 10(11) vp [n = 3]; 4 x 10(11) vp [n = 3]; 8 x 10(11) vp [n = 3]), with clear concentration-dependent increase in FVIII activity (range 160-510 mU/ml; plasma activity 16%-51% of normal). Peak activity was seen by Day (D) 5, with slow return to baseline by D28 (0.1-0.9% activity); in only 3/9 mice was loss of FVIII activity associated with development of anti-FVIII antibodies. Quantitative-PCR using genomic DNA isolated from D28 liver, spleen, heart, lungs, and kidney demonstrated the highest concentration in liver (approximately 10 genomes/cell), with little to no organ toxicity at early (D5 or 6) or late (D28) post-infusion time points. There was no evidence for spontaneous transgene excision or genomic integration in vivo as evaluated by quantitative PCR and genomic blotting. These data establish (i) the feasibility and applicability of developing high-titer Ad/AAV hybrid viruses for FVIII delivery using a small cellular promoter, (ii) the potential utility of this virus for generation of "gutted" monomeric and dimeric mAD/FVIII retaining AAV integration elements, and (iii) that the development of strategies for regulated Rep68/78 co-expression may provide a novel approach for excision, integration, and long-term FVIII transgene expression.

Dental health indices and caries-related microflora in children with severe haemophilia.

The purpose of this work was to investigate the prevalence of dental caries, bacterial dental plaque, gingivitis, enamel defects and caries- related microflora in children with severe haemophilia. Thirty-eight children with severe haemophilia (factor VIII and IX < 2 U dL(-1)) were recruited from Great Ormond Street Hospital for Children and matched for age, gender and ethnicity with healthy control children from the Eastman Dental Institute. Indices were recorded for decayed, missing, and filled teeth and surfaces in both the deciduous dentition (dmfs/dmft) and the permanent dentition (DMFS/DMFT). The plaque and gingivitis scores and developmental enamel defects were also recorded. The caries-related microflora was sampled and cultured for Streptococcus mutans, and Lactobacilli and Candida species. A significantly greater proportion of children with severe haemophilia were caries-free compared with the controls (36.7% vs. 13.3%; P=0.04). Both the DMFS and DMFT were significantly greater in the controls (3.6 and 2.8, respectively) compared with the haemophilia group, (0.8 and 0.7; P=0.007 and P=0.04). The plaque score for the permanent dentition only was significantly greater for the control children (24.2) compared with the haemophilia group, (10.2; P=0.04). The mean number of colony forming units of S. mutans was significantly greater in the control group compared with the haemophilia group (P=0.05). We conclude that children with severe haemophilia have a significantly lower prevalence of dental caries compared with matched, healthy controls.

A controlled neuropsychological study of HIV‐seropositive and HIV‐seronegative adolescent haemophiliacs

Sixty-four males with haemophilia were assessed with a series of neuropsychological tests and a structured interview for psychiatric symptoms. Thirty-one had been infected with human immunodeficiency virus (HIV) before the age of 18 and were in various stages of the disease at the time of testing and 33 were HIV negative. Sixteen male control subjects were recruited to match in age with the haemophilia group. The HIV-seropositive group were older than the HIV-negative group due to the cohort effect of the time of infection. Contrary to predictions from the known effects of HIV on the central nervous system the HIV-seropositive group performed better on many of the tests than the HIV-seronegative group. In some but not all of the tests this may have been an age effect. There was very little psychiatric morbidity, consistent with the view that high levels of psychological support provided by the haemophilia units can alleviate the effects of the illness on emotions and behaviour. These findings form a baseline for a 2-year follow-up study which is in progress.

Incidence of inhibitor development in a group of young hemophilia A patients treated exclusively with lyophilized cryoprecipitate

The incidence of neutralizing isoantibody formation to infused factor VIII in a cohort of 67 hemophilia A patients, born between January 1, 1971 and April 30, 1990, who had been treated exclusively with lyophilized cryoprecipitate, was 6% (5.3 per 1,000 patient years of observation). The age-dependent cumulative risk was 4.6% at 4 years of age and 6.7% at 8 years of age. Recent reports in patients treated with a variety of more pure concentrates show a much higher incidence of inhibitor formation and tend to be used as a reference when new concentrates are introduced. We believe that a patient group, such as the one studied here, is a more suitable reference population because these patients have been exclusively treated with a single factor VIII preparation.

Incidence of Inhibitor Development in a Group of Young Hemophilia A Patients Treated Exclusively With Lyophilized Cryoprecipitate

AbstractThe incidence of neutralizing isoantibody formation to infused factor VIII in a cohort of 67 hemophilia A patients, born between January 1, 1971 and April 30. 1990, who had been treated exclusively with lyophilized cryoprecipitate, was 6% (5.3 per 1,000 patient years of observation). The age-dependent cumulative risk was 4.6% at 4 years of age and 6.7% at 8 years of age. Recent reports in patients treated with a variety of more pure concentrates show a much higher incidence of inhibitor formation and tend to be used as a reference when new concentrates are introduced. We believe that a patient group, such as the one studied here, is a more suitable reference population because these patients have been exclusively treated with a single factor VIII preparation.

939 PHENOTYPIC AND FUNCTIONAL CHANGES OF LYMPHOCYTES IN HEMOPHILIACS

Changes in cellular immunity have been reported in hemophiliacs receiving lyophilized factor concentrate, T cell subsets, mitogenic responsiveness, and degree of hypergammaglobulinemia in healthy hemophiliacs were examined in order to determine the effect of product therapy on immune responsiveness of children with hemophilia (age range, 3-21 years). The study population was comprised of 21 hemophilia A patients receiving factor VIII concentrate, 10 hemophilia A patients receiving cryoprecipitate, 8 hemophilia B patients receiving factor IX concentrate and 20 healthy children receiving no blood products. The percentage of T4+ lymphocytes was decreased in all hemophiliacs regardless of therapy (p<0.05). Only patients with hemophilia A receiving factor VIII concentrate exhibited a concomitant increase in the percentage of T8+ lymphocytes and showed a significantly decreased T4/T8 ratio (p<0.05). Depressed mitogenic responsiveness to phytohemagglutinin and concanavalin-A was observed in both hemophilia A and B patients receiving factor concentrate (p<0.05). No correlation was observed between changes in the T4/T8 ratio or mitogen responsiveness relative to the amount of product received. Hypergammaglobulinemia of the IgG class was demonstrable in all hemophilia groups and correlated with age (p<0.05). Phenotypic and functional alternations of lymphocytes demonstrated in hemophiliacs are probably the result of chronic factor exposure, which becomes more pronounced with increasing age.