The Un-BLyS-Ful State: Blocking Factor VIII Inhibitor Development with BLyS Depletion

The development of neutralizing alloantibodies (inhibitors) to infused factor VIII (FVIII) remains the most significant complication of therapy in hemophilia A (HA). Despite some insights into genetic and environmental risk factors associated with inhibitor development, the immunological mechanisms behind this complication remain incompletely understood. Given that infused FVIII is likely encountered in the periphery, transitional B cell response to FVIII may regulate inhibitor development. Transitional B cell survival, maturation and proliferation are tightly regulated by the cytokine BLyS (B-lymphocyte stimulator). Elevated levels of BLyS have been described in both auto- and allo-immune disease processes and may be genetically determined in a subset of patients with lupus and multiple sclerosis. In prior experiments, we noted that BLyS levels are higher in HA patients with inhibitors as opposed to 10 other pro- and anti-inflammatory cytokines. However, BLyS levels normalized amongst those who underwent successful immune tolerance induction. Thus, we hypothesized that BLyS may regulate FVIII inhibitor development or persistence. Here, we present results from animal studies aimed at 1) preventing inhibitor development in naïve HA mice and 2) maintaining long-term tolerance.For prevention experiments, HA C57Bl/6 mice (n=8-10/group) were given a single dose of anti-BLyS neutralizing antibody (Sandy-2, Adipogen) or PBS control one week prior to immunization with recombinan...
Source: Blood - Category: Hematology Authors: Tags: 321. Blood Coagulation and Fibrinolytic Factors: The Clotting System in Inflammation, Immunity, and Cancer Source Type: research