The Impact of Clotting Factor Concentrates on the Immune System in Individuals With Hemophilia

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.

Clotting factor concentrates and immune function in haemophilic patients

Patients with haemophilia often exhibit a variety of disturbances in immune function. Although infections with HIV, hepatitis and other viruses no doubt contribute to these abnormalities, chronic exposure to extraneous proteins in clotting factor concentrates (CFCs) may also play a role. Numerous in vitro and ex vivo studies show that protein contaminants--such as immunoglobulins, fibrinogen and fibronectin--can depress various immune function indicators. Generally, such studies show that intermediate-purity CFCs are more inhibitory than very high-purity (e.g. monoclonal-purified) CFCs. In many, but not all, studies, the degree of immunosuppression correlates with the amount of intermediate-purity CFC administered over time. Among various indicators of immune function, CD4+ lymphocyte number is a marker for the progression of HIV infection, and maintenance of CD4+ number is associated with delayed progression. A number of studies suggest that, compared with intermediate-purity CFCs, use of very high-purity CFCs is associated with longer preservation of this class of lymphocytes. However, it remains to be seen whether this translates to improved long-term clinical outcomes. Further research is needed on the impact of CFCs on the immune system. For the time being, however, evidence to date favours the use of very high-purity products because they appear to preserve immune function and reduce the risk of infection with hepatitis and other viruses.

Frequency of human anti-FVIII antibodies in humanized SCID mice elicited by recombinant deleted factor VIII and by a plasma derived factor VIII

SCID mice were grafted with human PBL (hu-PBL-SCID) from healthy or haemophilia A donors. Those containing human and no murine Ig in their plasma, were injected with 100 U VIII:Ag of a plasma derived (pd) FVIII or recombinant deleted Factor VIII (FVIII deltaII) and with 10 microg of tetanus toxoid as control immunogen. The frequency and the intensity of the humoral specific responses were measured in 253 mice humanized with PBL from 13 different donors. There was no significant difference in the frequency or intensity of the anti-FVIII immune responses to pd FVIII and FVIII deltaII. Neutralizing antibodies were only detected in the plasma of mice humanized with cells from haemophiliacs having FVIII inhibitors in their blood. The immune responses observed in hu-PBL-SCID mice correlated with the immune status of the corresponding human donor.

Foreign-protein-mediated immunodeficiency in hemophiliacs with and without HIV

Hemophilia-AIDS has been interpreted in terms of two hypotheses: the foreign-protein-AIDS hypothesis and the Human Immunodeficiency Virus (HIV)-AIDS hypothesis. The foreign-protein-AIDS hypothesis holds that proteins contaminating commercial clotting factor VIII cause immunosuppression. The foreign-protein hypothesis, but not the HIV hypothesis, correctly predicts seven characteristics of hemophilia-AIDS: 1) The increased life span of American hemophiliacs in the two decades before 1987, although 75% became infected by HIV--because factor VIII treatment, begun in the 1960s, extended their lives and simultaneously disseminated harmless HIV. After 1987 the life span of hemophiliacs appears to have decreased again, probably because of widespread treatment with the cytotoxic anti-HIV drug AZT. 2) The distinctly low, 1.3-2%, annual AIDS risk of hemophiliacs, compared to the higher 5-6% annual risk of intravenous drug users and male homosexual aphrodisiac drug users--because transfusion of foreign proteins is less immunosuppressive than recreational drug use. 3) The age bias of hemophilia-AIDS, i.e. that the annual AIDS risk increased 2-fold for each 10-year increase in age--because immunosuppression is a function of the lifetime dose of foreign proteins received from transfusions. 4) The restriction of hemophilia-AIDS to immunodeficiency diseases--because foreign proteins cannot cause non-immunodeficiency AIDS diseases, like Kaposi's sarcoma. 5) The absence of AIDS diseases above their normal background in sexual partners of hemophiliacs--because transfusion-mediated immunotoxicity is not contagious. 6) The occurrence of immunodeficiency in HIV-free hemophiliacs--because foreign proteins, not HIV, suppress their immune system. 7) Stabilization, even regeneration, of immunity of HIV-positive hemophiliacs by long-term treatment with pure factor VIII. This shows that neither HIV nor factor VIII plus HIV are immunosuppressive by themselves. Therefore, AIDS cannot be prevented by elimination of HIV from the blood supply and cannot be rationally treated with genotoxic antiviral drugs, like AZT. Instead, hemophilia-AIDS can be prevented and has even been reverted by treatment with pure factor VIII.

Five myths about AIDS that have misdirected research and treatment

A number of widely repeated and factually incorrect myths have pervaded the AIDS research literature, misdirecting research and treatment. Five of the most outstanding are: 1) that all risk groups develop AIDS at the same rate following HIV infection; 2) that there are no true seroreversions following HIV infection; 3) that antibody is protective against HIV infection; 4) that the only way to treat AIDS effectively is through retroviral therapies; and 5) that since HIV is so highly correlated with AIDS incidence, it must be the sole necessary and sufficient cause of AIDS. A huge body of research, reviewed in this paper, demonstrates the falsity of these myths. 1) The average number of years between HIV infection and AIDS is greater than 20 years for mild hemophiliacs, 14 years for young severe hemophiliacs, 10 years for old severe hemophiliacs, 10 years for homosexual men, 6 years for transfusion patients of all ages, 2 years for transplant patients, and 6 months for perinatally infected infants. These differences can only be explained in terms of risk-group associated cofactors. 2) Seroreversions are common. Between 10 and 20 percent of HIV-seronegative people in high risk groups have T-cell immunity to HIV, and may have had one or more verified positive HIV antibody tests in the past. 3) Antibody, far from being protective against HIV, appears to be highly diagnostic of loss of immune regulation of HIV, and some evidence of antibody-enhancement of infection exists. 4) Non-retroviral treatments of HIV infection, including safer sex practices, elimination of drug use, high nutrient diets, and limited reexposure to HIV and its cofactors have proven to be effective means of preventing or delaying onset of AIDS. 5) Many immunosuppressive factors, including drug use, multiple concurrent infections, and exposure to alloantigens, are as highly correlated with AIDS risk groups as HIV. These data are more consistent with AIDS being a multifactorial or synergistic disease than a monofactorial one.

Purity of factor VIII concentrates and serial CD4 counts. The Transfusion Safety Study Group

Whether expensive high-purity factor VIII concentrates are required to slow CD4 decline in HIV-infected haemophiliacs is controversial. We examined CD4 counts among such cases treated with intermediate-purity and high-purity factor VIII. 36 subjects treated with high-purity concentrate for 6 months or more had a smaller decline in CD4 than 72 matched controls on intermediate-purity concentrate (two-sided p = 0.08). In a more complex analysis with 226 subjects, CD4 counts declined 3% less per 6 months with high-purity material than with intermediate product (p = 0.04). Thus concentrate purity may affect rate of CD4 change.