Clotting factor concentrates and immune function in haemophilic patients

Effect of factor VIII concentrate on leucocyte cytokine receptor expression in vitro: relevance to inhibitor formation and tolerance induction

Inhibitor formation in haemophilia patients receiving factor VIII (FVIII) concentrate is a serious problem requiring tolerance induction therapy. Inhibitor antibody formation is dependent on interactions between leucocyte cytokines with their corresponding receptors. To investigate this we studied the effect of FVIII on cytokine receptor expression using multiparameter flow cytometry and a whole blood stimulation assay. Upregulation of many cytokine receptors was inhibited by plasma-derived FVIII (pdFVIII) in a dose-dependent manner on T cells, B cells and monocytes although interleukin (IL)-4Ralpha and IL-7Ralpha were upregulated on T cells. The decrease in cytokine receptor upregulation on B cells in the presence of pdFVIII, may result in reduced antibody production. Inhibition of CD132 in the presence of pdFVIII may result in immune tolerance in some recipients of pdFVIII. The immunomodulatory effects of pdFVIII were dose and batch dependent, some being more inhibitory than others. The inhibitory effects of prednisolone with pdFVIII, on cytokine receptor upregulation, were additive. Cytokine receptor expression was not altered in the presence of human recombinant FVIII (rFVIII) concentrate. These findings may explain the reports of less frequent inhibitor antibody formation in some recipients of pdFVIII concentrates. The use of pdFVIII, particularly the more inhibitory batches, may be more suitable than rFVIII for tolerance induction protocols. A clinical study needs to be undertaken to determine the significance of these in vitro findings.

The effect of clotting factor concentrates on the immune system in HIV-negative haemophilics

Immune abnormalities have been reported in patients with haemophilia. Although infections with HIV and hepatitis viruses contribute to these abnormalities, chronic exposure to extraneous proteins in clotting factor concentrates (CFC) may also play a role. A number of studies suggest that the degree of immunological abnormalities correlates with the amount of intermediate purity CFC administered over time. The purpose of this study was to investigate whether there were cellular and humoral immunological abnormalities in haemophilics receiving intensive factor replacement therapy with intermediate purity CFC. For this purpose 48 severe haemophilics and 33 healthy controls were enrolled in this study. T and B lymphocytes, CD4+ and CD8+ cell counts, CD4/CD8 ratio, natural killer cells, active T cells were studied in prophylaxis group, on-demand therapy group and healthy controls. In the percentages and absolute counts of lymphocyte subgroups, no significant difference was found between three groups. We also investigated serum antitetanus IgG levels in these 48 haemophilics and the controls to evaluate the specific antibody response. Antitetanus IgG levels were significantly lower in haemophilics compared to healthy controls (P < 0.001). Additionally we evaluated the response to tuberculin skin test in 45 of 48 haemophilics vaccinated with BCG. The response to PPD test was significantly lower in haemophilics compared to the controls (P = 0.037). There was no response to tuberculin test, which is the best marker of delayed type hypersensitivity (DTH) reactions in 24% of haemophilics. In conclusion, although there was no significant change in the ratio of CD4/CD8 and lymphocyte subgroups, specific antibody responses and DTH tests were partially impaired in haemophilic patients receiving intermediate purity CFC.

The chemical bases of the various AIDS epidemics: recreational drugs, anti-viral chemotherapy and malnutrition

In 1981 a new epidemic of about two-dozen heterogeneous diseases began to strike non-randomly growing numbers of male homosexuals and mostly male intravenous drug users in the US and Europe. Assuming immunodeficiency as the common denominator the US Centers for Disease Control (CDC) termed the epidemic, AIDS, for acquired immunodeficiency syndrome. From 1981-1984 leading researchers including those from the CDC proposed that recreational drug use was the cause of AIDS, because of exact correlations and of drug-specific diseases. However, in 1984 US government researchers proposed that a virus, now termed human immunodeficiency virus (HIV), is the cause of the non-random epidemics of the US and Europe but also of a new, sexually random epidemic in Africa. The virus-AIDS hypothesis was instantly accepted, but it is burdened with numerous paradoxes, none of which could be resolved by 2003: Why is there no HIV in most AIDS patients, only antibodies against it? Why would HIV take 10 years from infection to AIDS? Why is AIDS not self-limiting via antiviral immunity? Why is there no vaccine against AIDS? Why is AIDS in the US and Europe not random like other viral epidemics? Why did AIDS not rise and then decline exponentially owing to antiviral immunity like all other viral epidemics? Why is AIDS not contagious? Why would only HIV carriers get AIDS who use either recreational or anti-HIV drugs or are subject to malnutrition? Why is the mortality of HIV-antibody-positives treated with anti-HIV drugs 7-9%, but that of all (mostly untreated) HIV-positives globally is only 1.4%? Here we propose that AIDS is a collection of chemical epidemics, caused by recreational drugs, anti-HIV drugs, and malnutrition. According to this hypothesis AIDS is not contagious, not immunogenic, not treatable by vaccines or antiviral drugs, and HIV is just a passenger virus. The hypothesis explains why AIDS epidemics strike non-randomly if caused by drugs and randomly if caused by malnutrition, why they manifest in drug- and malnutrition-specific diseases, and why they are not self-limiting via anti-viral immunity. The hypothesis predicts AIDS prevention by adequate nutrition and abstaining from drugs, and even cures by treating AIDS diseases with proven medications.

Adverse events in the prophylaxis of haemophilia

Whilst prophylaxis undoubtedly offers many advantages, the potential for adverse effects must also be borne in mind. Modern plasma-derived products have an extremely good safety record with regard to transmission of pathogens, although continuous vigilance is required as new pathogens continue to emerge, eg new variant Creutzfeldt-Jakob disease. There is no evidence that prophylactic treatment is associated with an increased incidence of inhibitors, and it is now recognized that genetic factors are the most significant in conferring susceptibility. Although subtle immunological abnormalities have also been observed in patients with haemophilia, there is no evidence that these are of any clinical significance. There has been a growing trend to use indwelling venous catheters for prophylaxis. The risk of infection has been appreciated for some time, although it has only recently been possible to quantify this with more precision. The risk of catheter-associated thrombosis is now recognized to be higher than hitherto appreciated. Whilst sporting activities are to be encouraged, there is a potential for significant trauma in children with prophylaxis, as plasma coagulation factor levels remain far below normal with the usual regimens.

Does hepatitis C virus cause severe liver disease only in people who drink alcohol?

Hepatitis C virus (HCV) infects about 170 million people worldwide, and has been portrayed in the media as a silent killer, incorrectly implying that cirrhosis and hepatocellular carcinoma are the certain final outcomes of infection. Results of numerous population-based surveys indicate that chronic HCV infection is highly prevalent in elderly people who, in most instances, do not develop end-stage liver disease. In individuals who do progress to cirrhosis and hepatocellular carcinoma alcohol plays a fundamental part, via mechanisms that result in increased viral replication, enhanced HCV quasispecies complexity, increased liver-cell death, suppression of immune responses, and iron overload. Although overlaps are present in the histological appearance of the liver in patients with hepatitis C who do and do not drink alcohol, histology could be of some help in revealing the role of alcohol in HCV disease progression even in people who deny drinking. Interventions and high-impact, continuous public-health campaigns are needed to persuade doctors and patients infected with HCV of the importance of abstaining from alcohol if risk of progression towards cirrhosis and hepatocellular carcinoma is to be reduced.

Experience with KOGENATE Bayer in surgical procedures

The study objectives were to assess the efficacy of KOGENATE Bayer (Kogenate FS) in achieving haemostasis during surgical procedures in patients with severe haemophilia A and to evaluate its safety when given in the doses needed for this purpose. Dosing for surgical procedures was in accordance with clinical practice in the management of haemophilia A patients during and after surgery. Efficacy was evaluated by estimated blood loss and assessment of haemostasis as determined by the attending physician. Safety was assessed by the incidence of adverse events related to study drug and the incidence of viral seroconversions. In total, 15 previously treated patients (PTPs) and seven previously untreated patients (PUPs)/minimally treated patients (MTPs) underwent 30 surgical procedures ranging from minor (port placement/tooth extraction) to major (orthopaedic endoprosthesis/brain tumour excision) surgery. The efficacy profile was good to excellent as assessed by the attending physician, and recorded blood loss was minimal to none. No adverse events were recorded that were related to study drug. No viral seroconversions were observed. In conclusion, KOGENATE Bayer was shown to be safe and efficacious in patients with severe haemophilia A during surgical procedures.

The natural history of chronic hepatitis C in a cohort of HIV-negative Italian patients with hereditary bleeding disorders

This study looked at 102 anti-hepatitis C virus (HCV)-positive, hepatitis B virus (HBV)-negative, and HIV-negative patients (median age, 45.1 years; range, 15-71) affected by hereditary bleeding disorders who have been infected with HCV for 15 to 34 years (median, 25.1). All these patients were infected before the mid 1980s because of non-virally inactivated pooled blood products. Fourteen patients (13.7%) were HCV-RNA negative with no signs of liver disease and were considered to have cleared the virus. Eighty-eight patients (86.3%) were HCV-RNA positive. The HCV genotype distribution was 1a in 20.5%, 1b in 36.4%, 2 in 17.0%, 3 in 15.9%, 4 in 3.4%, and mixed in 6.8% of cases. Twenty-four patients (23.5%) had serum cryoglobulins, symptomatic in 4 cases, and associated with liver disease and with genotype 1. Among the 88 HCV-RNA-positive patients, 15 (17.0%) had normal alanine aminotransferase levels and abdominal ultrasound, 61 (69.3%) had nonprogressive chronic hepatitis, and 12 (13.7%) had severe liver disease (6 [6.9%] liver cirrhosis, 4 [4.5%] hepatic decompensation, and 2 [2.3%] hepatocellular carcinoma) after a follow-up period of 25 years. There were 3 (3.4%) liver-related deaths. HCV genotype 1, patient's age at evaluation, duration of infection, and severity of congenital bleeding disorder were associated with more advanced liver disease. The results confirm the slow progression of HCV infection in HIV-negative hemophiliacs.

Factor VIII concentrate inhibits T helper type 2 cytokine production in vitro: relevance to inhibitor antibody formation

Inhibitor antibody formation in patients with haemophilia receiving factor VIII (FVIII) concentrate is a serious problem. T helper type 2 (Th2) cytokines are necessary for antibody production by B cells and have been shown to be produced predominantly by CD30(+)/CD45RO(+)/CD3(+) cells. We have previously shown that the Th2 cytokine, interleukin (IL)-6, is inhibited but IL-10 is upregulated, in the presence of plasma-derived FVIII (pdFVIII). To clarify further the overall effect of FVIII on Th2 cytokine production, the percentage of T cells expressing the CD30(+)/CD45RO(+)/CD3(+) Th2 phenotype was studied over 72 h and the production of the Th2 cytokines, IL-4 and IL-5, determined at 24 h in the presence of FVIII following whole-blood stimulation using multiparameter flow cytometry. The production of IL-4 and IL-5 by T cells was significantly inhibited in the presence of pdFVIII. The percentage of CD30(+)/CD45RO(+)/CD3(+) increased with stimulation of whole blood cultures over 72 h but was significantly inhibited by the presence of pdFVIII or TGF-beta at 72 h. The combined inhibitory effect of prednisolone (a commonly used immunosuppressive agent used to treat patients with inhibitors) with pdFVIII on T-cell CD30(+)/CD45RO(+) upregulation, was additive. There was no significant alteration in Th2 cytokine production or phenotype noted in the presence of recombinant FVIII (rFVIII) concentrate. Neutralizing antibody to TGF-beta significantly abrogated the inhibitory effects of pdFVIII on Th2 upregulation, indicating TGF-beta to be a major inhibitory component of pdFVIII on Th2 cytokine production. We now provide evidence that pdFVIII, by inhibiting Th2 cytokine production, may result in decreased antibody formation and may be more appropriate than rFVIII at reducing inhibitor formation. A clinical study needs to be undertaken to determine the significance of these in vitro findings.

Adenovirus-mediated factor VIII gene expression results in attenuated anti-factor VIII-specific immunity in hemophilia A mice compared with factor VIII protein infusion

Hemophilia A patients are typically treated by factor VIII (FVIII) protein replacement, an expensive therapy that induces FVIII-specific inhibitors in approximately 30% of patients with severe hemophilia. FVIII gene therapy has the potential to improve the current treatment protocols. In this report, we used a hemophilia A mouse model to compare the humoral and cellular immune responses between an E1/E2a/E3-deficient adenovirus expressing human FVIII directed by a liver-specific albumin promoter and purified recombinant FVIII protein infusion. Adenovirus-mediated FVIII expression did not elicit detectable CD4+ or CD8+ T cell responses and induced a weak antibody immune response to FVIII. In contrast, FVIII protein administration resulted in a potent anti-FVIII antibody response and moderate CD4+ T cell response. Furthermore, hemophiliac mice preimmunized with FVIII protein infusion to induce anti-FVIII immunity, and subsequently treated by adenovirus-mediated FVIII gene therapy, expressed therapeutic levels of FVIII despite the presence of low levels of anti-FVIII antibodies. No FVIII was detected in the plasma of mice with intermediate or high antibody levels, although anti-FVIII antibody levels in some vector-treated animals declined. The data support the hypothesis that liver-specific gene therapy-mediated expression of FVIII may be less immunogenic than traditional protein replacement therapy.

Lymphocyte subset abnormalities in multitransfused HIV-negative haemophilia A patients are not due to chronic hepatitis C virus infection

Several abnormalities of immune parameters have been described in HIV-negative haemophiliacs, including changes in numbers of T4 and T8 cells, T4/T8 ratio and numbers of activated T cells. To assess the contribution of hepatitis C to these abnormalities, we compared lymphocyte subsets in 20 HIV-negative HCV-positive haemophilia A patients and in 14 non-haemophiliacs with chronic hepatitis C with those in 18 healthy controls. In haemophilia patients, higher numbers of T lymphocytes and activated T8 cells, lower numbers of B lymphocytes and a normal T4/T8 ratio were seen. These differences were either not demonstrated in hepatitis C controls or were less pronounced and in the opposite direction. We conclude that haemophilia A patients showed abnormalities in lymphocyte subsets that could not be attributed to chronic hepatitis C.