Red blood cell phenotyping after transfusion: an in vitro model

Recipients red blood cell (RBC) phenotyping using serologic techniques, within 3 months of a transfusion, is considered unreliable. We conducted in vitro experiments to determine how long recipients RBC phenotyping results would be compromised. In vitro models were created to mimic in vivo posttransfusion ratios of "transfused" RBCs with either a single or a double dose of an antigen at 10-day intervals from day 0 to day 90 in hypothetical recipients with varying weights and hematocrits (Hct) receiving varying numbers of RBC units. In general, a reliable recipient RBC phenotype was possible earlier after transfusion in larger recipients, those with higher Hct, and those transfused with fewer RBC unit and if the transfused units had the antigen of interest in single, rather than double, dose. We believe that a reliable RBC phenotype, using routine serologic techniques, can often be obtained well before 3 months after transfusion. Similar studies with other donors, antigens, antisera, and methods and in actual patients will be useful.