Acute and delayed hemolytic transfusion reactions secondary to HLA alloimmunization

BACKGROUND

HLA antibodies may be directed against HLA antigens on RBCs, but these antibodies are generally not considered to be clinically significant in transfusion practice. A case of a multiparous woman who had hemolytic transfusion reactions due to HLA-related Bg antibodies is reported.

CASE REPORT

A 37-year-old woman was admitted with anemia. No unexpected RBC antibodies were identified. Two group O, D+ RBC units were transfused. Ten days later she returned with hemolysis and anemia. Two more RBC units were ordered, no unexpected RBC antibodies were identified, and two crossmatch-compatible units were issued. During the transfusion, the patient developed symptoms of an acute reaction, and the posttransfusion sample showed evidence of intravascular hemolysis.

RESULTS

Repeat RBC antibody screen showed anti-Bg. HLA antibody screen identified anti-HLA-A2, A28, B7, B7 cross-reactive group (CREG). The two RBC units from the first transfusion episode and one RBC unit from the second transfusion episode were HLA incompatible with the patient. No other cause for the hemolytic reactions was identified. The patient was later successfully transfused with one RBC unit from an HLA-compatible donor.

CONCLUSION

HLA antibodies should be considered in patients with hemolytic transfusion reactions when RBC-specific antibodies are not found to be the etiology.

Adverse reactions due to leucocyte and platelet antibodies

Each blood transfusion exposes the recipient to the hazards of immunisation to histocompatibility antigens as well as white cell and platelet antigens. As the number of transfusions received by a patient increases so too does the likelihood of the development of antibodies which may by their multispecific character effectively prevent lifesaving therapy in the future. Special steps can and should be taken to minimise the risks of immunisation in the group of patients who will be dependent on long term transfusion therapy. An extension of knowledge about the antigenic systems of leucocytes and platelets, including HLA, and the introduction of more specific tests for the detection of antibodies directed against them should assist in the provision of more appropriately matched blood components.