Monocyte CD14 response following endotoxin exposure in cotton spinners and office workers

Background: Monocyte cell surface CD14 acts as the major lipopolysaccharide (LPS) binding structure, and as such is of interest in the etiology of LPS induced disease. Methods: The objective was to assess change in monocyte cell surface CD14 and CD4+ CD25+ lymphocytes in a group of cotton workers exposed to LPS over a working week, and to compare this to changes in office workers. Twenty-five cotton workers and nine office workers were studied. Monocyte CD14 fluorescence was measured by flow cytometry, on samples taken pre-shift on a Monday morning (baseline/pre-exposure), and subsequently after 6 and 72 hr. The majority of cotton workers were exposed to at least 1 EU/m3 of endotoxin over a working shift, and some highly exposed (between 100 and 400 EU/m3). Results: After 6 hr of work in the mill, cotton workers developed a significant upregulation in CD14 in comparison to office workers (P=0.016), whereas CD14 expression had returned to levels not significantly differing from the office workers at 72 hr after first work exposure (P=0.426). Conclusions: We propose that CD14 expression on monocytes may help to determine the mechanism of action of lipopolysaccharide in producing respiratory ill health, and may ultimately play a role in monitoring the health effect associated with LPS exposure in the workplace.