Figure 6.

Inhibition of tumor growth by hDR5 reactive immune sera. A. Apoptosis induced by immune sera can be further amplified by IgG-mediated crosslinking. SUM159 cells were treated with 1% immune or non-immune sera for 30 min at 37°C and washed to remove unbound antibody, followed by incubation with goat anti-mouse IgG (α-IgG, 10 μg/mL) for 20h before Annexin V and 7-AAD staining. Relative to non-immune sera group, **p<.005. B. SUM159 cells were incubated with sera from vaccinated mice, or mAb631 (as described in Material and Methods), washed, and 3×10⁶ cells were injected s.c. into SCID mice. Animals were monitored weekly for tumor growth. The median time to palpable tumor was monitored. Tumor incidence in the hDR5 immune sera treated group (n=7) was significantly different from the control (n=8, p=0.02) or the mAb631 treated (n=8, p=0.03). C. Tumor growth rate was documented by weekly assessment of tumor volume as calculated by the XY²/2, X=long axis and Y=short axis. Statistical differences between the three groups are indicated.