Priming of cytokine release and increased levels of bactericidal permeability-increasing protein in the blood of animal facility workers

Objective: To investigate cellular immune responses in laboratory animal wo rkers who are exposed to high levels of animal allergens but also to other biologically active substances containing lipopolysaccharides (LPS), i.e., endotoxins. Methods: A survey among 20 animal facility workers and 20 match ed (gender smoking) controls was conducted using exposure measurements (end otoxin, colony-forming units of bacteria and fungi) and a questionnaire on respiratory symptoms. Blood samples were taken to determine the ex vivo who le-blood release of tumor necrosis factor-alpha (TNF) and interleukin-8 (IL -8) as well as plasma levels of LPS-binding protein (LBP), bactericidal per meability-increasing protein (BPI), the 75-kDa soluble TNF receptor (sTNFR7 5), and total/specific IgE. Results: Although exposure to endotoxin was low (range 0.05-2.8 ng/m(3)), a significant (P < 0.05) increase in plasma BPI (4-fold) and srTNF75 (1.2-fold) was found, suggesting a response to inhalat ion of LPS. Also, the capacity of blood leukocytes to release TNF and IL-8 in response to ex vivo exposure to workplace dust was increased. Data were not confounded by specific allergies, levels of IgE, smoking, or respirator y symptoms. Conclusions: A profound effect on the cellular immune response was seen in animal workers with low endotoxin exposure and a high antigenic load. It remains to be determined which other biologically active substanc e(s) are involved in this effect.