FIG. 1.

In vivo clearance of IgG-sensitized RBCs in guinea pigs treated with minimal effective doses of estrogens. Numbers represent the doses of estrogens used (in milligrams per kilogram per day). Red cell survival is the percentage of ⁵¹Cr-labeled IgG-senstized RBCs (± SEM) remaining in the circulation at each indicated time point. Clearance of IgG-sensitized RBCs at 120 min was significantly enhanced by Et at 0.01 mg/kg (P < 0.001), M at 1 mg/kg (P < 0.001), Ct at 1 mg/kg (P < 0.001), Pm at 0.25 mg/kg (P < 0.01), Ep at 5 mg/kg (P < 0.01), and E at 5 mg/kg (P < 0.01). Survival of heat-damaged RBCs was not significantly different in estrogen-treated animals from that in sham controls (no estrogen).