Effect of factor VIII concentrate on leucocyte cytokine production: characterization of TGF-beta as an immunomodulatory component in plasma-derived factor VIII concentrate

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Abstract
Clinical and subclinical immunological abnormalities have been reported in HIV‐seronegative haemophiliacs. The mechanisms by which these abnormalities arise remain unclear. As cytokines are important biological response modifiers, the effect of a FVIII concentrate on production of a range of cytokines, by a variety of cells, was investigated. A whole blood technique was used and the in vitro modulation of cytokine synthesis by an intermediate‐purity plasma‐derived factor VIII (pdFVIII) concentrate was analysed using multiparameter flow cytometry. In cell cultures exposed to pdFVIII, T cells showed reduced production of TNF‐α, IL‐2 and IFN‐γ; monocytes showed reduced production of TNF‐α, IL‐1α, IL‐1β, IL‐6, IL‐8 and IL‐12 but an increase in IL‐10 synthesis; IFN‐γ synthesis by NK cells was reduced. All changes in cytokine synthesis and the reduction in cell surface expression of CD69, a signal transduction molecule contributing to both cytokine and cytokine receptor synthesis, were in a dose‐dependent manner in cultures exposed to FVIII concentrate. These changes were characteristic of TGF‐β. Addition of anti‐TGF‐β to FVIII reduced these changes in T‐cell cytokine production, suggesting TGF‐β may be an important immunomodulatory agent in the pdFVIII concentrate. The Th2 cytokine bias shown in the presence of pdFVIII concentrate, in vitro, may explain the increase in rates of certain types of infections reported in these patients, which require Th1 cytokine production for an effective response.