Scheduling of denileukin diftitox treatment for optimization of CD4+ T-cell proliferation to rV-CEA/TRICOM (+rF-GM-CSF) vaccination in a self-antigen system. CEA transgenic mice were subcutaneously vaccinated on day 0 with 1 × 108 pfu rV-CEA/TRICOM (admixed with 1 × 107 pfu rF-GM-CSF). On day 28, CD4+ T cells were added to proliferation assays with 50 μg/mL CEA protein. Mean proliferation (± SD) was measured by 3H-thymidine incorporation of triplicate wells; nonspecific proliferation to β-Gal protein was subtracted from CEA-specific proliferation. A single intraperitoneal injection of 0.75 μg denileukin diftitox was administered to indicated groups (A) before (day −4), concurrent with (day 0), or after (day 3) vaccination or (B) on day −7, −3, or −1 before vaccination. Statistical evaluation was performed by repeated-measures one-way ANOVA using GraphPad Prism.
