Comparison of the PK(15)- and WEHI 164 (clone 13)-based bioassays for detection of porcine tumor necrosis factor.

OBJECTIVE: To determine relative sensitivities of the PK(15)- and WEHI 164(13)-based bioassays for detection of tumor necrosis factor alpha (TNF). SAMPLE POPULATION: Recombinant human, murine, and porcine INF, and serum from pigs given endotoxin IV. PROCEDURE: Two cell lines were used as targets for recombinant human, murine, and porcine TNF cytotoxicity bioassays. Pigs were given sublethal doses of endotoxin to obtain serum samples containing high activity of porcine TNF. Serum TNF activity was tested, using both cell lines. Viable cells were detected by addition of dimethylthiazol diphenyltetrazolium bromide after 18 to 20 hours' incubation with samples containing TNF. RESULTS: The 2 cell lines tested had different sensitivities to human, murine, and porcine TNF. Compared with WEHI 164(13) cells, PK(15) cells were 50 times less sensitive to murine TNF and 15 times less sensitive to human TNF. However, PK(15) cells were 4 times more sensitive to recombinant porcine TNF and 15 times more sensitive to porcine serum containing TNF. CONCLUSIONS: The PK(15) cell line was more sensitive to porcine TNF-mediated lysis than was the WEHI 164(13) cell line. The PK(15)-based TNF bioassay will be especially useful for study of infectious disease processes in swine, particularly where low activity of TNF exists.

Listeria monocytogenes infection increases neutrophil adhesion and damage to a murine hepatocyte cell line in vitro.

Several studies have reported that Listeria monocytogenes multiples within hepatocytes and that inflammatory neutrophils inhibit this intracellular growth in vivo. In the present study, we used a murine embryonic hepatocyte cell line (ATCC TIB73) as an in vitro model to investigate neutrophil-hepatocyte interactions. Murine peritoneal exudate neutrophils adhered more readily to L. monocytogenes-infected hepatocyte monolayers than to uninfected monolayers or monolayers infected with actA- and hly- mutants of L. monocytogenes. L. monocytogenes-infected TIB73 cells increased their surface expression of ICAM-1 as compared with uninfected TIB73 cells. Neutrophil adherence and oxidative stress to TIB73 cells were reduced by pre-incubating the hepatocyte monolayers with anti-ICAM-1 monoclonal antibody and diminished further by pre-incubating the peritoneal exudate neutrophils with an anti-CR3 monoclonal antibody.