Endotoxin-binding proteins in nasal lavage: evaluation as biomarkers to occupational endotoxin exposure

Exposure to endotoxin (LPS) can cause chronic respiratory disease, with sym ptoms that ore more pronounced after exposure-free periods. The aim of this study was to evaluate LPS-response modulating proteins in nasal lavage and plasma as biomarkers for exposure to airborne endotoxin. We applied nasal lavage, lung function and exposure measurements in a small group (n = 11) o f cotton workers during 6 weeks of observation (after 2 weeks free from exp osure) and ten external controls. Lipopolysaccharide binding protein (LBP) and bactericidal/permeability increasing protein (BPI) were measured in nas al lavage fluid (NALF) along with classic markers such as differential cell counts, Interleukin-8 (IL-8) and albumin, to evaluate their use as markers in endotoxin exposure. In all control subjects and cotton workers LBP and BPI were readily detectable in NALF, although a high intra- and intervariab ility was noted. At the exposure levels in this study (cotton dust, geometr ic mean (GM) = 1.10 mg m(-3); endotoxin, GM = 2869 EU m(-3)), plasma BPI an d BPI and LBP in NALF mere significantly (P < 0.05) different from external controls. In addition, within the group of cotton workers, during the meas urement period a significant increase was noted in BPI, albumin and BPI/LBP ratio in NALF (P < 0.05), while a significant decrease in total cell numbe rs was noted. However, none of the markers in NALF was correlated to the di fferent exposure indices used, based on personal endotoxin or dust exposure measurements. The data show that LBP and BPI are present in nasal lavage f luid and that these markers as well as their ratio increase during airborne endotoxin exposure in cotton workers.