Blood
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The clinical benefit of intravenous immunoglobulin (IVIG) preparations in the treatment of immune thrombocytopenic purpura (ITP) is supposed to be mediated by blockade of Fc gamma receptor--bearing phagocytes. In 2 experimental models for ITP, it is shown that the therapeutic efficacy of IVIG preparations is related to the IgG dimer content present in these preparations. A rat monoclonal antibody (mAb; MWReg30) directed to the murine platelet-specific integrin alpha(IIb)beta(3) (gpIIb/IIIa) was administered intraperitoneally either as bolus injection or continuous infusion. ⋯ IVIG predominantly consisting of monomeric IgG had no effect on platelet numbers. In conclusion, continuous infusion of MWReg30 induces thrombocytopenia in mice by enhancing Fc gamma receptor--mediated clearance of platelets. In this model, it is shown that IgG dimers present in IVIG preparations are responsible for the increase in platelet counts. (Blood. 2001;98:1095-1099)
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Parainfluenza virus (PIV) infections may be significant causes of morbidity and mortality in patients undergoing stem cell transplantation, but data regarding their impact on transplant-related mortality is limited. This study sought to determine the risk factors of PIV acquisition and progression to lower respiratory tract infection, their impact on transplant-related mortality, and the effectiveness of antiviral therapy. A total of 3577 recipients of hematopoietic stem cell transplantation (HSCT) between 1990 and 1999 were studied. ⋯ Corticosteroid administration thus drives the development of PIV pneumonia in a dose-dependent fashion, even among autologous HSCT recipients. Both upper and lower tract PIV infections are predictors of mortality after HSCT. Currently available antiviral therapy appears to be inadequate in reducing viral shedding or mortality once pneumonia is established. (Blood. 2001;98:573-578)
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Experimental allogeneic bone marrow transplantation (BMT) models using cytotoxic single-deficient (perforin/granzyme or Fas ligand [FasL]) and cytotoxic double-deficient (cdd) CD4(+) donor T cells have previously demonstrated roles for both effector pathways in graft-versus-host disease (GVHD). In the present study, the role of CD4-mediated antihost cytotoxicity in a GVH response is further examined across a complete major histocompatibility complex class I/II mismatch. As predicted, a double cytotoxic deficiency resulted in a clear delay in GVH-associated weight loss, clinical changes, and mortality. ⋯ Consistent with these observations, transplantation into 11.0-Gy recipients resulted in identical GVH lethality by equal numbers of B6 wild-type, B6-cdd, and B6-gld CD4(+) T-cell inoculum. In total, the findings indicate that aggressive host conditioning lessens the requirement for donor CD4(+) cytotoxic function in GVH responses soon after BMT. The present results thus support the notion of a role for cytotoxic effector function in donor CD4(+) T cells prior to GVH-induced tissue injury.
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Intracranial hemorrhage is the third most frequent cause of cerebrovascular disease, but few genetic risk factors have been associated with its development. Recently, it has been reported that some polymorphisms that affect clotting factors increase the risk for thrombosis. However, reports have analyzed the effect of polymorphisms influencing the hemostatic state in bleeding disorders insufficiently. ⋯ Finally, no significant differences were observed in the prevalence of factor XIII V34L polymorphism between patients and controls. Therefore, new genetic factors affecting the risk for spontaneous intracranial hemorrhage were identified. These data, together with the relevance of these polymorphisms in thrombotic diseases, support the idea that a polymorphism may play opposite roles in thrombosis and hemorrhage, suggesting an explanation for the high frequency of these polymorphisms in the general population.