Biodistributions of radioactivity in HEL xenograft-bearing athymic mice injected with ⁹⁰Y-DOTA-biotin or ²¹³Bi-DOTA-biotin after anti-CD45 BC8 Ab-SA conjugate and CA. HEL-xenograft-bearing mice were injected intravenously via the tail vein with 1.4 nmol of anti-CD45 BC8 Ab-SA conjugate followed 22 hours later with 5.8 nmol of CA and subsequently 2 hours later with 1.2 nmol of radiolabeled DOTA-biotin. Groups of 5 mice were killed at 3 time points after injection. The radioactivity in blood, tumor, and normal organs was measured by γ-counting, corrected for decay, and expressed as% ID/g of tissue. (A) ⁹⁰Y-DOTA-biotin uptake at 1 (□), 24 (■), and 72 (▨) hours after injection. (B-C) ²¹³Bi-DOTA-biotin uptake at 10 (□), 45 (■), and 90 (▨) minutes after injection with anti-CD45 Ab-SA without (B) or with DMPS (C). (D) ²¹³Bi-DOTA-biotin uptake at 10 (□), 45 (■), and 90 (▨) minutes after injection after delivery of nonbinding control Ab-SA conjugate.