PILOT-STUDY OF HLA ALLOIMMUNIZATION AFTER TRANSFUSION WITH PRESTORAGELEUCODEPLETED BLOOD PRODUCTS IN APLASTIC-ANEMIA

We have performed a pilot study to examine the incidence of alloimmuni zation using pre-storage leucocyte-depleted blood products (PLDP) in 1 6 previously transfused aplastic anaemia (AA) patients with no detecta ble HLA antibodies. A further eight AA patients with HLA antibodies re ceived HLA-matched PLDP, Leucodepleted apheresed platelets were obtain ed using either Cobe spectra or Haemonetics system with an integral pa ll. filter. Pall BPF4 filters were used for red cell preparation. Pati ents' sera were tested for HLA antibodies using lymphocytotoxicity (LC T). Patients who were HLA antibody negative by LCT at study entry were further tested with enzyme-linked immunoassay (ELISA). Out of 16 pati ents, two (12%) formed anti-HLA antibodies with a median follow-up of 9 months (range 1-15), but did not display platelet refractoriness to random donor platelets. Two patients were inadvertently transfused wit h non-leucodepleted blood products when later referred back to their l ocal hospital. Both subsequently demonstrated HLA antibodies by LCT an d became platelet refractory. These results contrast with a 50% incide nce of HLA alloimmunization in a control group of AA patients transfus ed prior to this study with non-PLDP. HLA antibodies could no longer b e detected by LCT in follow-up of three out of eight patients with HLA antibodies at study entry. Only one patient experienced non-haemolyti c febrile transfusion reactions (NHFTR). We conclude that PLDP reduce the risk of alloimmunization even in previously transfused AA patients , PLDP are associated with a low incidence of NHFTR, and all new AA pa tients should receive PLDP from diagnosis.