LOW INCIDENCE OF RED-CELL AND HLA ANTIBODY-FORMATION BY BONE-MARROW TRANSPLANT PATIENTS

Background: Bone marrow transplant (BMT) patients, although immunosupp ressed, are at risk for the development of red cell (RBC) and HLA anti bodies, and they often are given filtered blood in an effort to preven t the latter complication. This study attempts to determine the rate o f formation and the specificity of both RBC and HLA alloantibodies in this patient population. Study Design and Methods: BMT patients (148 r eceived autologous marrow; 45 received allogeneic marrow) from an 18-m onth period, including patients with leukemia (57 patients), lymphoma (54), breast cancer (68), myeloma (8), myelodysplastic syndrome (5), a nd aplastic anemia (1), were studied to determine the rate of alloanti body formation to RBC and HLA antigens. A total of 2410 RBC antibody s creens were performed. The patients received 3921 packed RBCs and 5915 single-donor platelet units; all were irradiated and administered via white cell-reduction filters. Results: Seven (3.6%) of 193 patients h ad RBC antibodies upon hospital admission. Four (2.1%) of 193 develope d RBC antibodies during the course of BMT: 3 patients had one RBC anti body and 1 patient had two RBC antibodies. RBC antibodies included ant i-E (n = 2), anti M (n = 1), anti-Jk(b) (n = 1), and anti-Lu14 (n = 1) . Thus, 98 percent of patients (189/193) did not develop new (182/186) or additional (7/7) RBC antibodies during BMT. BMT patients were also screened weekly for HLA antibody formation (60-cell panel). Upon admi ssion, 170 (85%) patients were negative. Of these, 8 (4.7%) developed persistent HLA antibodies (mean panel-reactive antibody score, 33 +/- 29%) and 9 (5.3%) were variably positive. Thus, in our setting and pop ulation, RBC antibody formation was 0.1 percent per unit transfused, a n the HLA alloimmunization rate was 5 to 10 percent. Conclusion: As RB C antibody screens are done every Monday, Wednesday, and Friday on thi s BMT service and as RBC antibody formation is low in these patients, screening for unexpected antibodies might be possible on a more infreq uent basis. Also, the rate of HLA alloimmunization in this population receiving filtered blood components is low.