RBCs from mHEL mice express HEL as a surface antigen. Blood was harvested from mHEL or C57BL/6 mice and stained with anti-HEL or anti-OVA antisera followed by a fluorescent secondary antibody (A). Blood from mHEL mice was stained with anti-HEL that was preincubated with HEL or OVA protein followed by secondary antibody (B-C). The mHEL-RBC⁺ anti-HEL specimen in panels A-C (solid line) represents the same sample displayed in multiple panels for clarity. Leukoreduced RBCs from mHEL and C57BL/6 mice were labeled with CM-DiI and DiO, respectively. The cells were then mixed and transfused into RAG^- KO mice. Peripheral blood was harvested, and the percentages (numbers in quadrants) of remaining transfused mHEL or C57BL/6 RBCs were determined by flow cytometry (D). Life span of transfused mHEL and C57BL/6 RBCs was determined by enumerating remaining mHEL or C57BL/6 RBCs by flow cytometry at the indicated time points (E-F). At each indicated time point, the level of mHEL on mHEL RBCs was determined by staining with anti-HEL and gating on labeled transfused mHEL or C57BL/6 cells (G). — indicates gating on mHEL RBCs; and - - -, gating on B6 RBCs. The experiments shown in this figure have been reproduced in at least 3 separate experiments. The data presented in this figure are representative results. Survival studies past 2 weeks have been performed twice with identical results.