Ozone enhancement of platinum asthma in a primate model

Three groups of adult male cynomolgus monkeys (Macaca fascicularis) were exposed to either 200 μg/m3 ammonium hexachloroplatinate [(NH4)2PtCI6], 200 μg (NH4)2PtCI6 concurrently with 1 ppm ozone (O3), or to 1 ppm O3 only. The animals were exposed by inhalation for 6 h per day, 5 days per week for 12 wk. The experimental design included methacholine preexposure and Na2PtCI6 bronchoprovocation challenge evaluations, Na2PtCI6 threshold skin tests, and sera for analyses of antibodies. Two weeks after the 12−wk exposures, these same indices were reevaluated. Baseline pulmonary function was not significantly affected by the exposure regimens; however, the combination of exposure to O3 and (NH4)2PtCI6 significantly reduced the concentration of platinum (Pt) salt and methacholine necessary to increase average pulmonary flow resistance (RL) 200% (EC200 RL). Ozone or Pt exposure alone had no significant effect on these parameters. Platinum and methacholine EC200 RL values were highly correlated for both Pt-exposed g...