KEL1 RBCs were transfused every 2 weeks x 3 into KEL2 recipients, in the presence of poly (I:C)

KEL1 RBCs were transfused every 2 weeks x 3 into KEL2 recipients, in the presence of poly (I:C). into wild type recipients, transfusion of KEL1 RBCs into KEL2 recipients or vice versa failed to lead to detectable anti-KEL1 or anti-KEL2 responses. Conclusions This murine model, with reproducible and clinically significant KEL glycoprotein alloantibody responses, provides a platform for future mechanistic studies of RBC alloantibody induction and consequences. Long term translational goals of these studies include improving transfusion safety for at risk patients. INTRODUCTION RBC alloimmunization is a clinically significant problem that affects men, women, and children alike. These RBC alloantibodies may increase morbidity and morality, putting patients at risk for acute and hemolytic transfusion reactions, hemolytic disease of the fetus and newborn, or delays in locating compatible blood. In fact, hemolytic transfusion reactions due to non-ABO antibodies were the 2nd leading cause of transfusion associated death reported to the US FDA last year1. 1/600 pregnancies are affected by RBC alloantibodies, with some women entering pregnancy with RBC alloantibodies due to prior transfusions and others becoming alloimmunized during pregnancy or after delivery2. Thus, RBC alloantibodies can be dangerous in transfusion and pregnancy settings alike. Outside of transfusion avoidance or limited phenotypic/genotypic matching, very few therapeutic strategies exist to prevent or to minimize the dangers of RBC alloimmunization. To date, much has been learned about the functional characteristics and immunogenicity of individual human RBC antigens3,4. However, the numbers of variables involved in each transfusion make studying factors influencing the formation of alloantibodies difficult. Such variables may include donor and recipient health status, donor and recipient genetics and antigenic differences, and donor unit preparation/storage. Furthermore, ethical and practical considerations limit in depth studies of the mechanisms of RBC alloantibody induction in humans. Lastly, human studies involving RBC clearance patterns have historically been limited by the method (radioactivity) of R-1479 RBC labeling, which allows a gross estimate of RBC clearance but limits in Rabbit Polyclonal to GCNT7 depth analyses of individual transfused RBCs. The therapeutic void for prevention and treatment of RBC alloimmunization is due, in part, to a lack of existing experimental models. In fact, the mechanism of action of the sole targeted immunomodulatory R-1479 therapy in existence (polyclonal anti-D or RhoGam) remains unknown5,6. Although a number of monoclonal anti-D preparations have been tested in humans7,8, no animal model with RBC specific expression of the complex D antigen exists to delve in depth into potential mechanisms. With the realization that native murine RBC antigens9,10 have not been thoroughly defined and are minimally immunogenic, our group has developed or worked with a number of transgenic murine models of RBC alloimmunization over the past decade11,12. Some have model antigen expression on RBCs (membrane bound hen egg lysozyme or mHEL)13, others have human RBC antigen expression (human glycophorin or hGPA)14,15 or Duffyb 16, and yet others have a hybrid of model and human antigens (hen egg lysozyme, ovalbumin, Duffyb or HOD) 17,18. Each animal model has its own set of strengths and weaknesses; however, none recapitulates all aspects R-1479 of a clinically significant human RBC antigen. The mHEL and Duffyb models have ubiquitous antigen expression, something not found in many human RBC antigens; stringent removal of contaminating WBCs and platelets is necessary for evaluation of RBC antigen responses. Anti-HEL antibodies generated in response to mHEL or HOD transfusions have been shown to result in selective removal of the HEL antigen instead of RBC clearance19; ongoing studies are further evaluating this phenomenon. The hGPA model results in anti-hGPA antibodies20 when donors and recipients are MHC matched and when recipients are pre-treated with poly (I:C), though anti-hGPA (e.g. anti-M family) antibodies in humans are rarely clinically significant. Interestingly, hGPA transfusion in the absence of inflammation leads to non-responsiveness and potentially antigen specific tolerance15. Passively infused anti-hGPA antibodies have been shown to lead to clearance of antigen positive RBCs21C24, with mechanistic studies ongoing. Thus, much has been learned and much remains to be learned from these models; however, none to date results in a reproducible, robust, and boostable alloantibody response in the absence of an adjuvant, leading to R-1479 RBC clearance with clinically significant sequelae. We sought to develop a new model of RBC alloimmunization with the above characteristics, ideally utilizing an existing human antigen..