FIG. 2.

Levels of T-cell proliferation in mice immunized with P. aeruginosa-pulsed DC CD4⁺ cells who also received P. aeruginosa-pulsed DC of spleen-derived CD4⁺ cells of mice which were primed with antigen (mice injected with DC pulsed with heat-inactivated or live PAO1) were increased compared to those of similarly immunized mice who received DC of spleen-derived CD4⁺ cells of mice which were not primed with antigen (unstimulated mice or mice injected with naive DC). C57BL/6 mice were injected intravenously with 2 × 10⁵ DC previously pulsed in vitro with live or heat-inactivated PAO1 (10 CFU/cell). Controls included naive mice or mice receiving naive DC. Two weeks following immunization, CD4⁺ cells were isolated from the spleens and coincubated for 48 h with irradiated DC previously pulsed with PAO1 for 48 h. CD4⁺-cell proliferation was evaluated by [³H]thymidine incorporation during incubation for 12 h. Proliferation is expressed as a stimulation index calculated in relation to CD4⁺ cells cultured with unpulsed DC.