Alloimmunization to red blood cell antigens by transfusion.

et al. Hereditary fibrinogen A alpha-chain amyloidosis: phenotypic characterization of a systemic disease and the role of liver transplantation. treatment, and prognosis of hereditary fibrinogen Aalpha-chain amyloidosis. Mutant fibrinogen A-alpha-chain associated with hereditary renal amyloidosis and peripheral neuropathy. and serial monitoring of human visceral amyloid deposits provide evidence for turnover and regression. resolution of proteinuria due to renal amyloidosis in a patient with rheumatoid arthritis treated with infliximab. et al. Clinical improvement and amyloid regression after liver transplantation in hereditary transthyretin amyloidosis. In their impressive report in a previous issue of Blood, Higgins and Sloan examined large patient databases and developed a model of alloimmunization to red blood cell antigens as a stochastic process. 1 They identified a subgroup of recipients that had a substantially increased risk of alloimmunization that was independent of common disease states, age, or number of alloantibodies previously formed. Their model suggests that approximately 13% of the transfusion recipient population are responders and at risk of forming red blood cell alloantibodies. The authors mention that there are reports that have identified a higher proportion of red blood cell alloantibodies in patients with sickle cell disease (SCD). They also state that they have excluded " any antibodies for these patients " from their report. Indeed, there are numerous studies that have found rates of alloimmunization in patients with SCD between 18% and 36%. 2-10 For example, Rosse et al reported an alloimmunization rate of 18.6% in 1814 patients with SCD who had been transfused. (Unlike Higgins and Sloan, they also noted a strong correlation between the prevalence of alloimmunization and the number of transfusions received.) 9 Garratty summarized 12 reports, encompassing 2818 transfused SCD patients, that collectively found a mean and median alloimmu-nization rate of 25%. 5 It would be interesting for Higgins and Sloan to comment on how their stochastic modeling aligns with the widely reported higher rate of alloimmunization in patients with SCD. Do they feel that the well-known disparities in antigen frequencies between SCD patients and the blood donor population, as well as the immunocompetence of SCD patients, fully account for the difference between these reports and their findings? References 1. Higgins J, Sloan S. Stochastic modeling of human RBC alloimmunization: evidence for a distinct population of immunologic responders. Clinical significance of RBC alloantibodies and autoantibodies in sickle cell patients who received transfusions. the effect of transfusion only phenotype-matched RBCs to patients with sickle …