Figure 6.

Shortening DNA antigen duration by depletion of natural Treg cells prior to DNA luciferase immunization. (A) At day 3, mice (n = 4 mice/group) were injected intraperitoneally with 1 mg of PC61 anti-CD25 monoclonal antibody, control antibody, or left as empty control group. At day 0, 50 μg plasmid luciferase was injected, and luciferase expressions were monitored by IVIS over the ensuing 28 days and were expressed as mean ± SD. Luciferase expression was significantly decreased from day 1 to day 14 during the ensuing 28 days’ observations in the anti-CD25 antibody injected group (p < 0.05, Student’s t-test). (B) Representative images of mice at day 2 and day 3, respectively, for luciferase expressions between CD25 depleted and non-depleted mice. (C) Mice (n = 4) were injected 50 μg DNA luciferase at both priming and recall phases (homologous boosted at day 42 following priming with DNA luciferase), respectively. IVIS monitoring at indicated time points. Dramatically reduced luciferase expression was determined at memory phase (less than 10 days). (D) Mice (n = 4) were injected 10⁸ adenovirus-encoded luciferase particles in priming phase; 42 days later, 50 μg DNA Luciferase (heterologous boost) was injected. Luciferase expressions were monitored by IVIS at indicated time points. The mean relative light unit (RLU) values expressed by groups of four mice ± SD.