Inhaled Lead Exposure Affects Tracheal Responsiveness and Lung Inflammation in Guinea Pigs During Sensitization

Total and differential white blood cells (WBC), and cytokines, levels in serum were examined in guinea pigs exposed to inhaled lead acetate. Different groups of guinea pigs including: control (group C), sensitized group (group S), and exposed animals to aerosol of three lead concentrations during sensitization (n = 6 for each group) were studied. Total and differential WBC counts of lung lavage, serum cytokine (IFN gamma and IL-4), levels and tracheal responsiveness to methacholine and ovalbumin were measured. All measured values were significantly increased except for IFN gamma/IL-4 ratio which was significantly decreased in nonexposed sensitized and those exposed to all lead concentrations compared to control group (p < 0.05 to p < 0.001). Most measured values in animals exposed to higher lead concentration were also significantly higher than group S except for tracheal responsiveness to methacholine and lymphocyte count. Lead concentration significantly increased in lung tissues of animals exposed to all three lead concentrations (p < 0.001 for all cases). These results showed that lead exposure during sensitization can induce greater increase in tracheal responsiveness, total WBC, eosinophil, neutrophil, and basophil counts as well as serum level of IL-4. It can also cause a decrease in lymphocyte count, IFN gamma level, and IFN gamma/IL-4 ratio especially in its high concentration. Therefore inhaled lead exposure may cause increased severity of asthma during development of the disease.