Figure 2

Neutralization of CD59 enhanced complement-mediated lysis. In A through D, Bcap37 and MCF7 cells (1 × 10⁵) were sensitized with 20 μg of rabbit antibody to β₂-microglobulin (anti-β2M) with or without specified doses of mAb-YTH53.1 (anti-CD59). Background LDH activity was obtained with unsensitized cells similarly incubated with 25% NHS for 4.5 hours to provide a numerical value that was subtracted from experimental values. Experimental antibody combinations are represented as follows: 1) 10 μg anti-β2M alone (28.0% lysis ± 1.7). 2) 20 μg anti-β2M alone (42.3% lysis ± 2.9). 3) 20 μg mAb-YTH53.1 alone (11.3% lysis ± 1.5). 4) 20 μg anti-β2M + 5 μg mAb-YTH53.1 (43.3% lysis ± 2.1). 5) 20 μg anti-β2M + 10 μg mAb-YTH53.1 (53% lysis ± 4.8). 6) 20 μg anti-β2M + 20 μg mAb-YTH53.1 (59% lysis ± 4.9).