Anti-Id and external beam irradiation has a significant benefit over either treatment alone in vivo. πBCL₁ are treated in vitro followed by growth in mice. Cells (10⁶/mL) were either treated with 2 Gy of external beam irradiation or remained untreated before being mixed with MoAb (0.5 μg/mL) as described, before being transferred into BALB/c (5/group). Each mouse received 10⁶ cells and 0.5 μg of MoAb as indicated in the key. Survival was monitored daily.