More rapid clearance of membrane complement regulator–deficient erythrocytes by the complement than by the FcR pathway.

Biotin-labeled Crry/DAF/C3^−/− erythrocytes (3 × 10⁸ per recipient) were either opsonized (+) or not (−) with 50 μg/mL mAb 34-3C, and transfused into FcγR^−/− mice (complement-mediated pathway) or C3^−/− mice (FcR-dependent pathway). The number of biotin-positive cells (expressed as percentage of total cells) in the recipient mice (n = 4 in FcγR^−/− mice experiment; n = 6 and n = 7 for antibody-sensitized and nonsensitized, respectively, in C3^−/− mice experiment) at 5 minutes (filled bars) and 3 hours (hatched bars) was determined. Very few of the antibody-opsonized cells were recovered from FcγR^−/− mice at 5 minutes and almost none at 3 hours. In contrast, a high percentage of the antibody-opsonized cells remained in the circulation of C3^−/− mice at 5 minutes and 3 hours. Error bars indicate means ± SE.