Alleviation of acute IgG-induced anemia by liposomal clodronate.

(A) Liposomal clodronate prevents the development of anemia induced by TER-119, a rat antimouse RBC antibody. Mice were injected with either liposomal clodronate or PBS (empty) liposomes. At 36 hours later, they were injected with anti-RBC antibody (TER-119). Mice were bled 36 hours after the antibody injection in order to determine blood hemoglobin concentration. One representative experiment out of 3 is shown. (B) Clodronate prevents the development of anemia induced by 34-3C (a mouse IgG2a autoantibody against murine RBCs), but not by 4C8, an autoreactive mouse IgM. Mice were injected as described in the legend to panel A, except with 150 μg 34-3C intraperitoneally, or 150 μg 4C8 intravenously. One representative experiment out of 3 is shown. Data are presented as means ± standard errors. (C) This effect of liposomal clodronate occurs despite a large amount of IgG bound to all circulating RBCs. RBCs from normal animals and animals injected with both clodronate and the indicated antibodies were washed 3 times in EDTA saline. The cells were then incubated with a goat anti–mouse/rat secondary antibody and analyzed by flow cytometry.