Transfusing special populations: Hemoglobinopathies:
Prophylactic antigen matching is very important when selecting RBCs for patients with sickle cell disease, for the following reasons:
- The risk of antibody formation is high, in part due to donor-recipient ethnic/antigenic disparity and increased levels of inflammation.
- Once formed, antibodies may not be detected on subsequent antibody screens. While the risk posed from antibody senescence (loss of detectability due to falling titres) applies to all patients, it is of particular concern in patients who receive transfusion support from multiple hospitals, which many patients with sickle cell disease are still obliged to do.
- The consequences of a delayed hemolytic transfusion reaction in patients with sickle cell disease are typically more severe than in other patients, and may include a vaso-occlusive pain crisis, or hyperhemolysis, a condition in which both transfused and autologous RBCs are destroyed, and additional transfusions (even if antigen-negative and crossmatch compatible RBC units) precipitate further hemolysis.
Prophylactic antigen matching can decrease the number of units available for transfusion. As the transfusion needs of patients with sickle cell disease may be significant, particularly for those requiring apheresis exchange transfusions, the most extensive matching is usually reserved for patients who have demonstrated a proclivity to antibody formation. The following approach is recommended:
| Scenario | Recommendation |
|---|---|
| For all patients with hemoglobinopathies | Baseline extended phenotype and/or genotype if possible |
| No history of alloantibodies | ABO, prophylactic matching for extended Rh (D, C, c, E, e) and K antigens |
| Known alloantibodies | ABO, matching for any clinically significant antibodies, plus prophylactic matching for extended Rh (D, C, c, E, e), K, Jka, Jkb, Fya and S antigens. (Note that unless a patient has made an anti-Fyb, matching for the Fyb antigen can be waived due to high prevalence of the GATA-mutation on the Fyb promoter, which silences of Fyb expression of RBCs only) |
Compernolle V, et al. Red blood cell specifications for patients with hemoglobinopathies: a systematic review and guideline. Transfusion 2018,58(6):1555-1566.
Prophylactic antigen matching is also frequently recommended for patients with thalassemia and occasionally for patients with myelodysplastic syndromes. Typically, the degree of prophylactic matching for these lower-risk populations is limited to Rh (D, C, c, E, e) and K antigens, even if antibodies to other antigens have been detected. Practices vary by region, however.
Finally, consideration should be given to how much caution should be exercised in matching patients with hemoglobinopathies for low-frequency antigens. For most patients, hospital transfusion services rely on crossmatch compatibility to exclude units that are positive for any low-frequency antigens that a patient has developed antibodies to. In patients chronically receiving large volumes of blood, however, a higher degree of precaution may be warranted, by ensuring that any unit issued has been confirmed by phenotyping or genotyping to be negative for the antigen in question.
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