Pulmonary response of mice to aqueous cotton dust extract

Objective: To determine the pulmonary response of mice to acute exposure of aqueous cotton dust extract (CDE). Design: CDE was made from a standard cotton mill dust. Under mild anaesthes ia, 0.05 ml of CDE was instilled intratracheally in balb/c mice. The same v olume of sterile isotonic saline was instilled in controls. After 1, 5 and 10, days animals were given am overdose of pentobarbital by intraperitoneal injection, and the upper thorax was opened to expose the trachea, An incis ion was made and cannulae was inserted. Bronchoalveolar lavage (BAL) was do ne by instilling, phosphate buffer saline. Total and differential counts we re done. The lavage supernatant was assayed for protein. Setting: The laboratory of Division of Pulmonary and Critical Care Medicine , Duke University Medical Center, USA. Animals: Balb/c mice. Main outcome measures: Post-exposure acute effects at bronchoalveolar level . Results: Total and differential cell counts in BAL fluid were significant ly higher in CDE exposed compared to controls (P<0.01). The total mean valu es (expressed as cells x 10(4)) after exposure for days 1, 5 and 10 were 19 3.4+/-8.6, 177.8+/-7.7 and 113.5+/-6.4 respectively versus controls (41.6+/ -3.4). Differential counts (cell no. x 104) revealed 124.3+/-6.8, 94.2+/-7. 9, 19.9+/-3.5 polymorph neutrophils (PNM) and 67.3+/-7.1, 81.6+/-9.4, 90.2/-8.6 macrophages (AM) on days 1, 5 and 10 respectively compared to control s 2.8+/-2.3 (PMN) and 37.2+/-1. I (AM), Analysis of protein (mg/ml BAL flui d) demonstrated a significant increase on exposure for days 5 and 10 (0.8+/ -0.05 and 0.9+/-0.6 respectively versus controls, 0.09+0.01, p<0.01). Conclusion: Acute exposure to CDE causes influx into the air spaces of infl ammatory leukocytes accompanied by an increase in lung permeability (eviden ced by the presence of protein in BAL fluid). In cotton mill workers, the a bove factors may contribute to the development of chronic byssinosis by as yet undefined agent(s) in cotton dust.