EBRT and anti-Id mAb therapy in BCL₁ and A31 lymphoma. Groups of 5 age- and sex-matched BALB/c (A) and CBA (B) mice were inoculated with BCL₁ (10⁵) or A31 (10⁶) lymphoma cells, respectively, by intravenous injection on day 0. Mice were then treated on day 10 with 5 Gy EBRT, with or without anti-Id mAb (500 μg BCL₁; 100 μg A31) given by intravenous injection 3 to 4 hours after EBRT. Survival was monitored daily. Both the BCL₁ and A31 tumors show similar results to the effects of EBRT with modest increases in survival of around 15 to 20 days after 5 Gy. The differences in sensitivity to anti-Id therapy between the BCL₁ and A31 models can be clearly seen, with the anti-Id alone providing 40 days additional survival over control animals, but no long-term survivors in the A31 model (B). In contrast, in the BCL₁ model, anti-Id provided very modest improvements in survival of around 8 days with EBRT providing approximately 15 days over the control animals. The addition of anti-Id mAb to 5 Gy EBRT in the A31 model however provided long-term protection with a highly significant increase in survival over controls and anti-Id alone (P < .01); however, the addition of anti-Id to 5 Gy EBRT in the BCL₁ model provided just 2 to 3 days over EBRT alone. This experiment is representative of 1 of 3 identical experiments performed.