Abstract
Development of antibodies (Ab) that inhibit the procoagulant function of factor VIII (fVIII) seriously complicates the treatment of hemophilia A patients. It also causes acquired hemophilia, a rare yet serious autoimmune disease. The design of effective fVIII-specific tolerizing procedures will require elucidation of the role of the different CD4+ T cell subsets that drive inhibitor synthesis. To examine the contribution of Th1 and Th2 cells in the anti-fVIII Ab response, we measured the concentration of Th1- and Th2-driven anti-fVIII IgG subclasses in 17 patients with severe hemophilia A and 18 patients with acquired hemophilia. We found that both congenital and acquired hemophilia patients had similar and comparable proportions of Th1- and Th2-induced anti-fVIII Ab, suggesting a more important role of Th1 cells in the immune response to fVIII than previously appreciated. The distribution of anti-fVIII IgG subclasses was stable for periods of up to six months. More intense anti-fVIII Ab responses and higher inhibitor titers correlated with a predominance of Th2-driven subclasses. In contrast, Th1-driven anti-fVIII Ab were predominant in patients who had low anti-fVIII Ab concentrations, even when this was the result of successful immune tolerance or immunosuppressive therapy, which had caused drastic reduction or disappearance of inhibitors. Thus, synthesis of Th2-driven inhibitors occurs when the anti-fVIII Ab response is intense, while Th1 cells may be involved in the long-term maintenance of anti-fVIII Ab synthesis.
Original language | English (US) |
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Pages (from-to) | 568-575 |
Number of pages | 8 |
Journal | Thrombosis and Haemostasis |
Volume | 88 |
Issue number | 4 |
DOIs | |
State | Published - Oct 1 2002 |
Keywords
- Acquired hemophilia
- Antibodies
- Factor VIII
- Hemophilia A
- Th1 cells
- Th2 cells