Evaluation of the measurement of leukotriene B-4 concentrations in exhaledcondensate as a noninvasive method for assessing mediators of inflammationin the lungs of calves

Objective-To determine whether measurement of an inflammatory mediator in e xhaled condensate could provide a noninvasive method for evaluating lungs o f calves. Animals-84 calves less than or equal to 2 months old. Procedure-Concentration of leukotriene B-4 (LTB4) was evaluated in the exha led condensate of healthy calves and calves with experimentally induced res piratory tract infections. For collection of samples of exhaled condensate, the total amount of exhaled air was directed into a cooled double-jacketed tube. Each tube was sealed and stored at -80 C. The LTB4 concentration was measured, using an ELISA. Results-In exhaled condensates of clinically healthy calves, normally distr ibuted and highly reproducible LTB4 concentrations (mean +/- SD, 116.1 +/- 55.4 pg/ml) were measured. After experimentally induced infection with Past eurella multocida serovar D, LTB4 in exhaled condensate increased significa ntly (mean, 179% increase), compared with basal concentrations before infec tion; this increase in LTB4 was significantly correlated with deterioration in lung function. In 2 of 4 calves experimentally infected with bovine res piratory syncytial virus, the LTB4 concentration in exhaled condensate incr eased (300 to 400% increase), compared with baseline values, which was asso ciated with development of bronchial hyperresponsiveness after infection. Conclusions and Clinical Relevance-Collection of exhaled condensate is tole rated well by carves and is an acceptable method for obtaining fluid from e xhaled air originating from the lungs. This method provides alternatives fo r diagnosing and evaluating treatment of naturally acquired and experimenta lly induced diseases of the lungs and airways in carves.