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 workers 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 matched (gender, smoking) controls was conducted using exposure measurements (endotoxin, colony-forming units of bacteria and fungi) and a questionnaire on respiratory symptoms. Blood samples were taken to determine the ex vivo whole-blood release of tumor necrosis factor-alpha (TNF) and interleukin-8 (IL-8) as well as plasma levels of LPS-binding protein (LBP), bactericidal permeability-increasing protein (BPI), the 75-kDa soluble TNF receptor (sTNFR75), 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 inhalation 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 respiratory 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 substance(s) are involved in this effect.