Anti-KEL glycoprotein antibodies are generated in response to transfused KEL2 RBCs. WT and KEL2 recipient mice were transfused with KEL2 RBCs, and anti-KEL glycoprotein levels were evaluated by flow cytometry posttransfusion. (A) Flow cytometric crossmatch method for analysis of serum antibody levels. MFI, mean fluorescence intensity. (B) Serum IgG levels were determined by flow cytometric crossmatch in WT (open circles) and KEL2 (solid squares) recipients at specific time points after transfusion. (C) Composition of antisera passively infused in subsequent experiments. These data are representative of 3 independent experiments, with 3-5 animals/group/experiment; error bars indicate standard deviation.