Cytokine Responses In Whole Blood Assay In Veterans With Agriculture Work Exposures

Abstract

RATIONALE: Agriculture exposures are associated with increased risk of chronic obstructive pulmonary disease (COPD). Endotoxin exposure in agricultural environments is associated with lung disease. Our objective was to evaluate responsiveness to endotoxin stimulation in an in vitro whole blood assay and its association with COPD in an agriculturally exposed cohort. METHODS: Veterans with ≥ two years agricultural work exposure participated in this case-control study. Cases are veterans with COPD defined as FEV1/FVC ratio < 70% on spirometry post-bronchodilator. Controls did not have COPD as assessed by spirometry nor other significant lung conditions. Whole blood assay (WBA) was done with 2 ml heparinized blood mixed with 2 ml of media and stimulated with increasing doses of LPS (0 – 1 ng/ml). Samples were incubated at 37°C for 24 hours, centrifuged, supernatants harvested and frozen until assayed for cytokines by ELISA. Cytokine values were log transformed. Repeated measures ANOVA was used to examine the association between LPS dose and group (case or control) and the interaction of dose with group. All p values were adjusted for age. RESULTS: There were 272 participants, 110 cases with COPD and 158 controls. Baseline demographics (gender, age, race) were similar between cases and controls. LPS-stimulated -α TNF production showed a significant dose effect (p <0.0001) and a significant difference adj α production than cases between study groups (p =0.0119) with controls having a greater capacity for TNFadj . There was no evidence of a