We studied the relationship between CD14 expression on monocytes and lower respiratory tract symptoms and lung spirometry in endotoxin exposed cotton workers. Spirometry and CD14 monocyte expression were measured in 39 workers on Monday (pre and 5 hours into shift) and Thursday (mid-shift) of the working week. Eight (20%) were classified as symptomatic (one or more work related lower respiratory tract symptoms). Twelve operatives (35%) had a fall of Fev1 and 11 workers (31%) of FVC of more than 5% during the working week. The percent change in CD14 expression (0-5 hours and 0-96 hours) was smaller in symptomatic workers but did not reach statistical significance compared to asymptomatic workers. Pearson's correlation coefficient between percent change in FVC (but not Fev1) and percent change in CD14 expression (0-96 hours) was significant (r=0.36, 0=0.046). Workers with FVC (but not Fev1) decline greater than 5% were more likely to have a smaller increase in CD14 expression at 5 hours (r=-0.89; p=0.017). A smaller change in across shift (but not across week) CD 14 expression on monocytes was correlated with greater decline in across week FVC. The trend was similar but did not reach statistical significance for both Fev1 across week change and symptomatic status.

The results of this small pilot study suggest that CD14 as a marker of endotoxin exposure may relate to the physiological change occurring in workers effected by their working environment.