Leukocyte numbers in circulating blood after dexamethasone, APAS, or busulfan administration. Mice were exposed to aerosolized OVA (1%) for 8 weeks and treated with either (A) dexamethasone (2 mg/kg administered intraperitoneally thrice weekly, before each day of exposure), (B) APAS (0.1 mL undiluted, administered intramuscularly twice weekly), or (C) busulfan (25 mg/kg administered intraperitoneally once fortnightly) throughout the period of exposure. Each point represents the mean and vertical lines the standard error of the mean of 3 to 5 observations.