Presentation on theme: "Case # 2 Clinical progress: 2009 HLA typing: no sibling match Hb S: 27-40%anti-S, anti-Jk(b) TCD velocities conditional range: < 200 cm/s Liver iron content."— Presentation transcript:
Case # 2 Clinical progress: 2009 HLA typing: no sibling match Hb S: 27-40%anti-S, anti-Jk(b) TCD velocities conditional range: < 200 cm/s Liver iron content (MRI):6.7 mg Fe/g RBC transfusion # 16 Commenced Deferasirox (oral Fe chelator) 2010 Hb S: 16-28% Brain MRI/MRA: moderate narrowing of A1 segment of ACA Blood bank:DAT weakly POS anti-IgG (probable autoAb)
Transfusion in Patients with Haemoglobinopathies (Sick Kids approach) Thalassemia (including congenital anemia like Diamond Blackfan Syndrome) and sickle cell disease Extended red cell phenotyping before first transfusion: – Rh (C, E, c, e), K1(Kell), Fya, Jka, (Jkb, S in SCD patients) Patient already transfused – Hypotonic saline (0.3% NaCl will lyse normal cells but not sickle cells) AABB Technical Manual 15 th edition Method 2.16 – Molecular genotyping – Family studies Prophylactic antigen matching: Thalassemia: K negative SCD: Rh and K matched, Fya, Jk, (S) if alloimmunized (No need for prophylactic Fyb matching Why not Fyb?
Fy(a-b-) Phenotype Frequency – Very rare (0%) in Caucasians and Asians – 68% in Africans Mutation in the promoter region of FYB (–33 T>C), which disrupts a binding site for the erythroid transcription factor GATA-1 and results in the loss of Fy expression on RBCs. Because the erythroid promoter controls expression only in erythroid cells, expression of Fy proteins on endothelium is normal in people with Fy(a–b–) RBCs. To date, all blacks with a mutated GATA box have been shown to carry FYB, therefore Fyb is expressed on their nonerythroid tissues. This explains why Fy(a–b–) individuals make anti-Fya but not anti-Fyb. Immunohematology 2004;20:37-49
The Duffy Antigen/Receptor Chemokine locus Comprised of 2 exons, spanning ~2 kbp in the region of chromosome 1q22-23 The single gene is responsible for the expression of Duffy antigens on RBCs and other non-erythroid tissue Promoter GATA-1 box mutation is responsible for the Fy(a-b-) RBC phenotype (pseudo-null) The gene product has no obvious function on the surface of RBCs; null RBCs appear to function normally FY affords protection from malarial invasion It has been proposed that the gpFy modulates chemokine levels in the blood; regulation of inflammation by scavenging chemokines
Transfusion in Patients with Haemoglobinopathies (Sick Kids approach) Start with SAGM units (prestorage leukoreduced) 15 to 20 ml/kg, SAGM red cells have hct approx 0.6 SCD: Units tested by sickle test (sickle negative for exchange transfusions) Repeated allergic reactions: pre-med Recurrent allergic reactions: plasma-reduce Frequent allergic reactions: Washed red cells from CBS: 24 hours shelf-life Currently, no Sick Kids patients on washed cells
Case #3 Female, born in 1980, sickle cell disease B pos, C-E-c+e+, K-, Fy(a-b-), Jka(a+b+) 1998: no antibody, transfused 3 units 1999: anti-K, anti-C, anti-E, autoantibody Sept 1, 2004, transfused 2 units, O neg, C- E- K- S- Fya-, crossmatch compatible Sept 14, 2004, 3 units B pos, C- E- K- S- Fya-, crossmatch incompatible
Case #3 (2004) Anti-IH – 4+ with group O cells by Sal I.S., 37 0 C and IAT – 1-2+with group B cells – Negative to weak with O h (Bombay) cells Testing with O h cells CellIS37 0 CIAT H-, M- 0w1 H-, M+N+w23 H-, M+N -243
Anti-IH I antigen: subterminal portion of the oligosaccarides that are eventually converted to H, A, and B antigens Most normal adult RBCs are I-positive H antigen is the substrate for A and B antigens H antigen expression: O > A 2 > B > A 1 B > A 1 > A 1 B The most common cold autoagglutinins are directed against the Ii blood group The most commonly encountered cold autoagglutinin recognizing complex ABH-Ii antigens is anti-IH Anti-IH does not generally interfere in pretransfusion testing done at 37 0 C, but may be picked up in MTS-gel Anti-IH is usually not clinically significant, anti-IH causing hemolytic transfusion reaction is very rare but has been reported. Transfusion 2000:40;828
Case #3 (2005-2006) Anti-IH not detectable Autoantibody Recommended for transfusion: group B, C- E- K- M- Fya- May 5, 2006, transfused 2 units O pos, C- E- K- Fy(a-b-) S-, MTS compatible, Hb 70 to 99 g/L May 15, 2006, Hb to 50g/L Strongly reactive with all cells tested, except for 2 Group B Rh null cells Episode of hyperhemolysis, eventually recovered
Antibodies to high prevalence antibodies Red cell alloantibodies – k, Kp b, Lu b, Js b – Jk3, U – African ethnicity: SsU, Js b, At a (Augustine), Hy (Holley), Jo a (Joseph) 1.Phenotype patient’s RBCs (Rh and others) 2.Antigen negative cells 3.Enzymes and chemicals Antibodies to reagent/preservative ABH antibodies – Group O patient, think Bombay or para Bombay – Non group O patient, think IH (more common in A 1, A 1 B, less common A 2, B, A 2 B)
Summary Phenotype patient before 1 st transfusion If transfused, hypotonic saline for SCD, molecular genotyping and family studies Autoantibodies are common SCD patients can make unusual alloantibodies When investigating for high incidence antibodies, do not forget ABO and reagents Clinical information including patient’s ethnic background
References Guidelines for Antibody Investigation. AABB 2010 Judd’s Methods in Immunohematology, 3 rd edition, AABB Press 2008. The Blood Group Antigen Facts Book, 2 nd edition, 2004, Reid & Lomas-Francis, NYBC Applied Blood Group Serology 4 th edition. Issitt 1998.
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