Alloimmunization: A review and recent insights into pathogenesis

1. Alloimmunization:A review and recent insights into pathogenesis Jessica Hata, MD 6/14/2013

2. 4 month old girl • Previously healthy, full term baby • Admitted with hepatosplenomegaly, fever, and pancytopenia • No prior transfusions • Typed as A Rh-positive • WBC 3.5, Hgb 7.0, PCV 23, pts 119 • received 5 U pRBCs and 1 U platelets

3. Day 14 Type and Screen • blood type: A Rh-positive • Ab screen: positive, anti-K1 and anti-E (!) • DAT + (IgG (4+) and anti-C3d (1+)) • Eluate: positive; Anti-Jka (!) • Segments tested: Jka, K1, E + RBCs • Molecular Genotype: Jka, K1, E - • No evidence of hemolysis • DDx: maternal-placental or Breast milk transmission vs neonatal alloimmunization vs false positive

5. Soluble IL-2 Receptor significantly elevated Treated with 4 weeks of Amphotericin B; Itraconazole therapy for 3 additional months Urine Histoplasma/ Blastomycosis antigen elevated Hospital Course Bone Marrow Biopsy

6. Outline • Alloimmunization Review • How do neonates/ infants differ? • Effects of immunogenetics on responder/ nonresponder status • Role of inflammation in red blood cell alloimmunization • Neonatal alloimmunization and a potential link to Histoplasmosis?

7. Basic Immunology

8. RBC Alloimmunization • Potential occurrence with blood product transfusion, pregnancy, or organ transplantation • An infrequent event: 2.6-2.9% in large series • Rates of alloimmunization to all antigens are higher in certain disease states • Immunization rates to other sources of foreign antigen (including vaccines and microbial infections) often approaches 100% • Acute HTRs, delayed H/STRs, and costly, time-consuming evaluations in the blood bank! Curr Opin Hematol 15:631–635 Arch Pathol Lab Med 1995;119:42–45 Br J Haematol 1995; 91:1000–1005

9. Neonatal Alloimmunization • In vitro studies show minimal Ig production • ? poor interaction between T and B cells • Relative immunodeficiency of the neonatal state: an increased ratio of T suppressor cells to T helper cells • Exceedingly rare and reported in only isolated case reports • The exact pathophysiologic mechanism is unknown.

10. AABB Standards

11. Neonatal Alloimmunization & Infection

12. Alloimmunity can be induced through exposure to microbial antigens that mimic the 3D structure of the alloantigen Microbial sequence data looks similar to human blood group antigens Molecular Mimicry? BLOOD, 2010; 115(19):3988-3996

13. Outline • Alloimmunization Review • How do neonates/ infants differ? • Effects of immunogenetics on responder/ nonresponder status • Role of inflammation in red blood cell alloimmunization • Neonatal alloimmunization and a potential link to Histoplasmosis?

14. Rate of Additional Antibody Formation After Transfusion in Non-Chronically Transfused Alloimmunized Patients 1° Ab formation in non-chronically transfused patients ~1% Repeat transfusion in alloimmunized patients >20% 15/653 patients experienced >11 additional transfusions without forming additional Ab The formation of the first antibody identifies “high responders” against subsequent alloantigenic challenges Transfusion. 2006;46:630-635

15. Advantages to Elucidating Risk Factors for Alloimmunization • Focused phenotypic /genotypic matching of RBCs for chronically transfused “responder” patients • Limit wasted resources matching “nonresponders” • Rational basis for development of therapeutic interventions to prevent RBC alloimmunization • OR use available drugs to block known inflammatory cascade signals around time of transfusion

16. Effects of Immunogenetics on Responder/Nonresponder Status • Vast majority of blood group antigens consist of a single AA polymorphism bet. donor and recipient • Each MHC variant (determined by HLA) will present different peptides from a given protein • 100% DRB1*04 in pts immunized to Fya (Transfusion 2006; 46:1328–1333) • Higher DRB1*01 and DQB1*05 in pts immunized to Jka (Transfusion 2005; 45:956–959) • Anti-K assoc with multiple DRB1 types (Transfusion 2006; 46:1328–1333)

17. Outline • Alloimmunization Review • How do neonates/ infants differ? • Effects of immunogenetics on responder/ nonresponder status • Role of inflammation in red blood cell alloimmunization • Neonatal alloimmunization and a potential link to Histoplasmosis?

18. Paradigm of Humoral Immunity • Patient must be antigen negative and exposed to that antigen • Patient must encode an HLA capable of presenting a representative peptide • Additional environmental stimuli  ? Role of inflammation

19. Sources of Inflammation in RBC Transfusion • Few inflammatory activators of microbial origin • Prestorage leukoreduction decreases the risk of donor cytokines • Synthetic chemicals (i.e. plastic of bag) or breakdown products of senescent RBCs • Inflammatory status of the recipient • 10 mo with JRA developed anti-E, Fya, and Jka following transfusion of one unit (N Engl J Med 2007; 357:2092–2093) • 16-yr with JRA and macrophage-activation syndrome developed anti-Cw, E, K, Jkb , S, M, and Lea following the transfusion of two units (Transfusion 2007; 47) • Pt with SLE developed 5 alloantibodies after a single transfusion (Mollison’s blood transfusion in clinical medicine. 11th ed.) • Sickle cell disease?

20. Mouse Model • RBCs transfused from mHEL donor mice into wild-type recipients • 100 μL of leukoreduced RBCs was injected via tail vein • 3-6 hours before transfusion, recipients were injected intraperitoneally with either poly(I:C) in buffer or buffer alone Current Opinion in Hematology 2008, 15:631–635 Transfusion 2006; 46:1526–1536.

21. Pretreatment with poly(I:C) significantly increased alloimmunization to transfused RBCs Current Opinion in Hematology 2008, 15:631–635 Transfusion 2006; 46:1526–1536.

22. Outline • Alloimmunization Review • How do neonates/ infants differ? • Effects of immunogenetics on responder/ nonresponder status • Role of inflammation in red blood cell alloimmunization • Neonatal alloimmunization and a potential link to Histoplasmosis?

23. Question and Study Design • Do patients with Histoplasmosis have a higher rate of alloimmunization? • A comprehensive review of the standard derivative deidentified medical record database (from 1998 to present) at Vanderbilt University Medical Center was undertaken to identify patients with Histoplasmosis and concomitant alloantibodies.

24. Patients with Histoplasmosis have a 5% alloimmunization rate compared to healthy adults

25. Conclusions • Alloimmunization is rare overall and even more rare in neonates • Severe inflammation and infection may induce alloantibody formation • Patients with Histoplasmosis have a 5% alloimmunization rate compared to healthy adults (2.6-2.9%) • Conservative transfusion practices, including offering phenotypically matched RBCs to patients with clinical or laboratory evidence of a high inflammatory state, may be prudent.

26. References • Hoeltge GA, Domen RE, Rybicki LA, Schaffer PA. Multiple red cell transfusions and alloimmunization. Experience with 6996 antibodies detected in a total of 159,262 patients from 1985 to 1993. Arch Pathol Lab Med 1995;119:42–45. • Heddle NM, Soutar RL, O’Hoski PL, et al. A prospective study to determine the frequency and clinical significance of alloimmunization posttransfusion. Br J Haematol 1995; 91:1000–1005. • DePalma, L et al; Presence of the red cell alloantibody anti-E in an 11 week old infant; Transfusion 1992; 32: 177-179. • Schonewille H, van de Watering LMG, Brand A. Additional red blood cell alloantibodies after blood transfusions in a nonhematologic alloimmunized patient cohort: is it time to take precautionary measures? Transfusion. 2006;46:630-635 • Noizat-Pirenne F, Tournamille C, Bierling P, et al. Relative immunogenicity of Fya and K antigens in a Caucasian population, based on HLA class II restriction analysis. Transfusion 2006; 46:1328–1333 • Reviron D, Dettori I, Ferrera V, et al. HLA-DRB1 alleles and Jk(a) immunization. Transfusion 2005; 45:956–959. • Tyler LN, Harville TO, Backall DP. Multiple alloantibodies after transfusion in an infant treated with Infliximab. N Engl J Med 2007; 357:2092–2093

27. References cont. • Zantek ND, Abdullah N, Pary PP, et al. Development of multiple red blood cell alloantibodies in a pediatric patient with juvenile rheumatoid arthritis and macrophage activation syndrome. Transfusion 2007; 47 (Supplement):136A • Mollison’s blood transfusion in clinical medicine. 11th ed. Klein HG, Anstee DJ, editors. Blackwell Publishing; 2005. • Zimring JC, Hendrickson JE. The role of inflammation in alloimmunization to antigens on transfused red blood cells. Current Opinion in Hematology 2008, 15:631–635 • DePalma L.; Review: red cell alloantibody formation in the neonate and infant: considerations for current immunohematologic practice; Immunohematology 1992; 8(2) 33-37. • Marsh et al. Naturally occuring anti-Kell stimulated by E Coli enterocolitis in a 20 day old child. Transfusion.1978; 18(2): 149-154. • Hendrickson JE, Desmarets M, Deshpande SS, et al. Recipient inflammation affects the frequency and magnitude of immunization to transfused red blood cells. Transfusion 2006; 46:1526–1536 • Hata JL, Johnson MS, Booth GS. Neonatal alloimmunization: a rare case of multiple alloantibody formation in a patient with disseminated histoplasmosis. Transfusion 2013; 53 (1140)