Abstract
Our experience in several cases has suggested that the use of the fully automated compatibility testing system AutoVue to detect donor-type antigens on red blood cells (RBCs) early after ABO-mismatched allogeneic stem cell transplantation (SCT) causes a delay compared to the use of the tube test. In this study, we investigated the differences between the two methods.
We selected a patient with blood type O who underwent bone marrow transplantation (BMT) from an HLA-matched sibling donor with blood type A. We centrifuged the patient's blood and separated the RBCs as follows: the thin top layer, and the upper, middle, and bottom layers according to the specific gravity of each. We then investigated the level of A1 antigen on RBCs in each layer. On day 32 after BMT, AutoVue could detect A1 antigen abundantly only in the thin top layer. The tube test estimated the titer of A1 antigen as ×32 before centrifugation, but after centrifugation as ×64 in the thin top layer, compared to ×8 in the other layers. On day 35, AutoVue could detect A1 antigen in the bottom layer. Two months after BMT, AutoVue and the tube test detected equal A1 antigen titer from the upper to bottom layers. We speculate that most of the donor RBCs remained immature within the early reticulocyte stage with low-level gravity early after BMT, so they were concentrated abundantly in the upper layer after centrifugation. Using AutoVue, a sample is generally aspirated from the bottom layer RBCs after centrifugation, which might delay the detection of donor-type antigens early after BMT.
In conclusion, using the thin top layer of RBCs might allow much earlier detection of donor-type antigens after SCT. Further, monitoring of donor-type antigens may be better done using whole RBCs that are mixed well.
