Biodistribution of trace-labeled ¹²⁵I-MoAb in BCL₁-carrying mice. Matched groups of mice, which had been injected IV with BCL₁ cells (10⁶) 14 days previously, were injected IV with 500 μg of ¹²⁵I-MoAb. The MoAb under investigation included: ▪, anti-Id; •, anti-MHCII; ▴, anti-CD22; and ⧫, control IgG2a. At the intervals shown, the animals were killed, blood samples obtained immediately postmortem, and the various organs (as shown) removed for weighing and estimation of radioactive content. Results are expressed as the percentage of the injected dose of ¹²⁵I-MoAb per gram of tissue recovered (% ID/g; Materials and Methods). For reasons of clarity, the anti-CD22 MoAb results are shown for the spleen only. Each point shows the mean and range for four or five animals investigated. These results represent one of two similar experiments.