RIT of BCL₁ using radioiodinated and unlabeled anti-B cell MoAb. (A) Composite graph showing results from three individual RIT (minimum of 40 animals per group) performed under the same experimental conditions. Mice were given 10⁶ fresh BCL₁ cells IV on day 0 and then treated with MoAb (500 μg with or without approximately 5 MBq ¹³¹I) 4 days later. (B) Groups of 10 BCL₁-bearing mice were treated as in Fig 2A, but with 750 μg of MoAb (with or without approximately 7.5 MBq of¹³¹I) on day 4. Treatments included: Control IgG (⋆);¹³¹I-control IgG (⧫); anti-MHCII (TI2-3; ○, •); anti-Id (□, ▪); anti-CD19 (⌓;); anti-CD22 (▵, ▴); and anti-MHCII MoAb (N22; ▿, ▾). The solid and open symbols represent MoAb labeled with and without radioactive iodine, respectively. Results with the anti-MHCII MoAb (○, •) are shown in both (A) and (B). Animal survival was monitored daily. Control ¹³¹I-IgG1 MoAb had a very small, but statistically significant therapeutic effect (P < .01).