A potential association of an interferon gene signature with RBC alloimmunization in sickle cell disease

Abstract

RBC transfusion can lead to the production of alloantibodies against RBC antigens. RBC alloimmunization can result in hemolytic events and severely limit the availability of compatible RBCs. Patients with sickle cell disease (SCD) have the highest rate of alloimmunization, compared to any other disease population. However, mechanisms underlying this increased frequency are poorly understood. Inflammation in the recipient has been shown to promote alloimmunization in mice and humans. In mouse transfusion models, type 1 interferons (IFNα/β) and interferon-stimulated genes (ISGs) have been shown to promote alloimmunization. Given the chronic inflammatory state in patients with SCD, we hypothesized that SCD patients may also have an IFNα/β gene signature that may contribute to the increased frequency of alloimmunization. To test this hypothesis, we measured the expression of multiple ISGs, including myxovirus resistance protein 1 (MxA) and Siglec-1 by whole blood immunoassay and flow cytometry, respectively. MxA and Siglec-1 levels were significantly elevated in SCD patients, compared to transfused controls. We then determined the degree to which ISG expression correlated with alloimmunization frequency by linear regression. There was a trend toward elevated MxA expression in patients with 1 or more alloantibodies. Patients with 2 or more alloantibodies had significantly elevated MxA compared to non-alloimmunized transfused patients. These findings suggest the presence of an IFNα/β gene signature in patients with SCD and warrant further investigation of the contribution of IFNα/β pathways toward the profoundly elevated frequency of RBC alloimmunization in patients with SCD.