Figure 1.

Kinetics of leukocytic infiltration in a murine model of chronic allergic asthma. (A) Female BALB/c mice were sensitized by intraperitoneal injection of 100 μg ovalbumin (OVA) in alum on Days 0 and 13. Mice were then challenged with an aerosolized solution of 5% OVA in PBS (or PBS alone) seven times between Days 19–28, and then three times per week for 4 weeks. Groups of mice were either killed 1 day after the final aerosol challenge (Acute), or housed for an additional 4 weeks without OVA challenge (Chronic Phase). An acute response was then reactivated by an additional aerosolized OVA challenge (Reactivation). (B) Leukocytic infiltration was assessed in the airways by flow cytometric analyses of bronchoalveolar lavage (BAL) fluid collected at three time points: 24 hours after the final repetitive challenge (Acute), 3 weeks into the chronic phase (Chronic), and 24 hours after the final reactivation challenge (Reactivation). Data show the mean ± SEM for numbers of leukocytes at the Acute, Chronic, and Reactivation time points. A Student t test was used to establish significant differences between the OVA and PBS groups (n = 6–12 mice per group). **P < 0.005. ***P < 0.0005.