LACK OF CLINICAL-SIGNIFICANCE OF ENZYME-ONLY RED-CELL ALLOANTIBODIES

In a retrospective study on samples from 10,000 recently transfused pa tients, 35 samples were found to contain an antibody that reacted with ficin-treated red cells but was not demonstrable by low-ionic-strengt h saline solution and indirect antiglobulin test (LISS-IAT). In those 35 patients, the specificity of the antibody was such that each patien t would have been transfused with antigen-negative blood had the antib ody reacted in LISS-IAT. Tests on red cells from the units already tra nsfused showed that 19 patients had among them received, by chance, 32 antigen-positive and 74 antigen-negative units. The remaining 16 pati ents had among them received 57 units that were, again by chance, all antigen negative. One patient given antigen-positive blood suffered a delayed transfusion reaction; in two others the antibodies became LISS -IAT active after transfusion. However, similar changes to the LISS-IA T-active state were seen with two antibodies of patients given only an tigen-negative blood. Also found in the 10,000 patients were 28 clinic ally insignificant antibodies, 77 sera in which the antibody was too w eak to identify, and 216 autoantibodies that reacted only with ficin-t reated red cells. These data support a belief, generally held in the U nited States but not necessarily elsewhere, that the use of protease-t reated red cells for routine pretransfusion tests creates far more wor k than the accrued benefits justify.