RELEASE OF TUMOR-NECROSIS-FACTOR-ALPHA FROM BOVINE ALVEOLAR MACROPHAGES STIMULATED WITH BOVINE RESPIRATORY VIRUSES AND BACTERIAL-ENDOTOXINS

The release of tumor necrosis factor-alpha (TNF-alpha) from cultured bovine alveolar macrophages (BAM) was evaluated following stimulation of BAM with bovine herpesvirus-1 (BIIV-1), parainfluenza-3 (PI-3) virus, bovine respiratory syncytial virus (BRSV), Escherichia coli 0111:B4 endotoxin, Pasteurella haemolytica type 1 endotoxin, Pasteurella multocida endotoxin, and virus/endotoxin combinations. A cytotoxic assay system using Georgia bovine kidney cells as targets was used to measure TNF-alpha activity. The cytotoxic activity was neutralized by an anti-human TNF-alpha monoclonal antibody. Stimulation of BAM with 1 median tissue culture infectious dose (TCID(so)) of live or ultraviolet (UV)-inactivated PI-3 virus/cell resulted in release of TNF-alpha in significantly (P < 0.05) higher amounts than sham-induced BAM. The quantities of TNF-alpha released after live or UV-inactivated BHV-1 or BRSV induction were not significantly higher than sham-induced BAM. E. coli 0111:B4, P. haemolytica type 1 and P. multocida endotoxins stimulated TNF-alpha release in a dose-dependent manner. Sequential exposure of BAM to 1 TCID(so) per cell of either live BHV-1, PI-3 virus or BRSV and then 5-mu-g ml-1 of either E. coli 0111:B4, P. haemolytica type 1 or P. multocida endotoxin caused a significant (P < 0.05) reduction in detectable TNF-alpha in seven of nine virus/endotoxin combinations tested, when compared with 5-mu-g ml-1 of endotoxin alone. Parainfluenza-3 virus/endotoxin combinations stimulated higher TNF-alpha release when compared with other virus/endotoxin combinations. Five out of six test animals had serum-neutralizing antibodies to PI-3 virus, one out of six had serum-neutralizing antibodies to BHV-1, and two out of six had serum-neutralizing antibodies to BRSV, suggesting a possible relationship between serum neutralizing antibodies and TNF-alpha release from in vitro cultivated BAM.