Introduction & Aims:
Chylothorax is the presence of chyle in the pleural space from thoracic duct damage. Conventional teaching suggests that chyle is bacteriostatic. No study has examined the biological role of chyle.
Methods:
Bacterial growth: Clinical strains of Streptococcus pneumoniae (n=10), Staphylococcus aureus (n=5) and Klebsiella pneumoniae (n=5) were grown in whole or cell-free chyle samples (n=14) for 12 hours. Viable counts (colony forming unit/mL) were assessed by spot-plating method.
Cell proliferation: Mesothelial/mesothelioma cells (n=4) were maintained in RPMI with 30% of chyle (v/v; n=34) for 48 hours. Cells were stained with 2% methylene blue and the absorbance was measured at 650nm.
Cytokine content: Concentrations of six cytokines (IL-8, IL-6, IL-1β, MCP-1, VEGF, VEGF-C) associated with formation of pleural fluid and pleural infection were determined by ELISA.
Results:
S. pneumoniae strains proliferated rapidly in chyle samples (by median fold change of 994.8) and faster than standard pneumococcal culture medium (THB+17%FCS – median fold change of 367.7, P< 0.0001). S. aureus isolates, but not K. pneumoniae, proliferated in chyle samples (median fold change of 201.4 and 1.334, respectively). In all the mesothelial/mesothelioma cell lines tested, chyle induced a median of 2 to 4-fold increase in proliferation compared to serum-free media controls. Chyle contains high levels of IL-8 (median of 96.95), IL-6 (1455), IL-1β (340.3), MCP-1 (1757), VEGF (676.1), VEGF-C (2210).
Conclusion:
Chyle is biologically active, potently promotes pneumococcal growth, and proliferation of mesothelial/mesothelioma cell lines.