Macrophage-depletion abrogates KEL antigen loss in anti-KEL–treated recipients, but not HEL antigen loss in anti-HEL–treated recipients. (A) Recipients were treated with clodronate or empty (control) liposomes before passive immunization with either anti-KEL or anti-HEL antibodies, or PBS control, followed by transfusion of labeled HOD × KEL RBC. (B) HOD × KEL RBC survival at the indicated time points posttransfusion. Transfused HOD × KEL RBC were stained for the level of detectable KEL antigen (C), HEL antigen (D), or Ter119 antigen (E). Means ± SD shown. ****P < .0001, **P < .01, and ns by 2-way ANOVA with Dunnett multiple comparison test (B) and 1-way ANOVA with Tukey multiple comparison test (C-E). Data shown include 7 to 8 mice per group and are representative of 2 independent experiments.