CLARA CELL PROTEIN CC16 AS A BIOLOGICAL MARKER OF LUNG INJURY AMONG QUARRY WORKERS EXPOSED TO PM2.5

Abstract

Objective: evaluation of the use of Clara cell protein (CC16) level in serum as an early indicator of the adverse respiratory health effects of particulate matter (PM2.5) exposure.Methods: Detailed assessment questionnaire was used for interviewing 54 individuals divided into workers exposed to particulates in the atmosphere of stone quarriesand a control group. The studied population was subjected to clinical examination and pulmonary function testing in order to diagnose airway diseases and lung irritation. Laboratory investigations were done in the form of Clara cell protein and immunoglobul in A (IgA) estimation in serum using the immunoassay technique. Results: According to the thorough occupational history and clinical examination,respiratory system affection was detected among the exposed population in the form of frequent asthmatic attacks, chronic bronchitis and chronic obstructive pulmonary disease. Pulmonary function tests demonstrated marked decrease in the expiratory flow rate 25-75% (FEF 25-75%) suggesting irritation and affection of the small airways correlating to duration of exposure more than smoking index. Estimation of the pneumoprotein CC16 which is produced by the epithelial cells in terminal bronchioles revealed marked elevation in serum of exposed group (149.61 ± 22.64 pg/mi) than among the control group (107.08 ± 12.18 pg/ml). Similarly, the humoral immune defense involving the secretory immunoglobulin A (slgA) predominant in mucosal secretions was markedly elevated among the exposed than the control groups with mean values of 372.41 ± 232.87 IU/ml and 143.76 ± 83.531U/ml, respectively. The serurn CC 16 and IgA were both significantly negatively correlated with flow rates.Worth-mentioning, is the increased CC 16 serum levels with ageing which influences the functionality of the lungs and immune systern as evidenced by the decline in lung volumes, lung capacity and flow rates and by decreased IgA in serum. Conclusion: The results suggest that damage of Clara cells in the small airways and the increased epithelial barrier permeability are ultimate consequences of exposure to particulates in air at the workplace. Accordingly, the elevated serum CC16 asa result of increased diffusion of this type of pneumoprotein into the circulation might be used as an early non-invasive biological indicator for lung affection. Aim of the Work: This study was designed to investigate the cellular and humoraldefense mechanisms of the respiratory tract in workers exposed to particulate air pollution in quarries in an attempt to evaluate the importance of using CC16 as a biologic marker for respiratory injury in comparison to pulmonary function tests.