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  • Author or Editor: Dagmar E. Frank x
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Abstract

Objective

To develop a model to study the kinetics and relative amounts of cytokines produced by liver cells during enteric infection.

Design

Salmonella enteriditis lipopolysaccharide (LPS)-or live S choleraesuis-stimulated isolated livers from clinically normal pigs and pigs with active acute phase response.

Animals

7- to 14-day-old salmonellosis-free pigs, 4 to 12/group.

Procedure

Livers were removed and perfused with oxygenated Krebs-Henseleit solution for 30 minutes and with S choleraesuis or LPS added for 7 minutes. Livers were then perfused with 500 ml of fresh solution in a closed loop procedure for 180 minutes. Perfusate samples were collected for tumor necrosis factor-α (TNFα) and interleukin 6 (IL-6) bioassays.

Results

Tumor necrosis factor-α values remained constant during perfusion of normal livers and increased in those exposed to LPS. Interleukin 6 values increased in perfusate from normal livers from 30 to 150 minutes, then decreased. In livers from pigs with an active acute phase response, TNFα values were reduced; IL-6 appeared by 2 minutes and decreased after 25 minutes.

Conclusions

Isolated livers could be kept viable for 3 hours, and IL-6 and TNFα could be measured by the bioassays used.

Clinical Relevance

Model can be used for studying and modifying the response of liver cells to infective agents. (Am J Vet Res 1996;57:472–476)

Free access
in American Journal of Veterinary Research

SUMMARY

Cattle persistently infected with bovine viral diarrhea (bvd) virus have decreased neutrophil and lymphocyte functions. We reevaluated these functions and further characterized the inhibition of persistent bvd virus infection in neutrophils, using sensitive kinetic assays. In addition, the influence of in vitro incubation of neutrophils with recombinant bovine interferon gamma (rBoifn gamma) and in vitro incubation of lymphocytes with recombinant bovine interleukin-2 was evaluated.

Significant (P < 0.05) decrease in random migration under agarose, Staphylococcus aureus ingestion, cytochrome-C reduction, iodination, antibody-independent cell-mediated cytotoxicity, oxidant production, and cytoplasmic calcium flux were observed in neutrophils from cattle persistently infected with bvd virus, compared with noninfected control cattle. Incubation of neutrophils from noninfected controls with rBoifn gamma significantly (P < 0.05) decreased random migration under agarose, cytochrome-C reduction, and cytoplasmic calcium flux. Neutrophils from cattle persistently infected with bvd virus also had decreased random migration under agarose after incubation with rBoifn gamma; in addition, antibody-independent cell-mediated cytotoxicity, elastase release, and cytoplasmic calcium flux were significantly enhanced. The rBoifn gamma induced significantly (P < 0.05) different effects on chemotaxis, cytochrome-C reduction, iodination, and cytoplasmic calcium flux of neutrophils from infected and control cattle. The rBoifn gamma was more effective at improving the function of neutrophils from cattle persistently infected with bvd virus, compared with neutrophils from controls.

Lymphocytes from infected cattle had decreased histogenesis in response to phytohemagglutinin, concanavalin A, and pokeweed mitogen. Incubation of those lymphocytes with recombinant bovine interleukin-2, with no mitogen present, significantly (P < 0.05) increased incorporation of [3H]thymidine. However, the response of lymphocytes to mitogen stimulation was not significantly increased by the presence of recombinant bovine interleukin-2, indicating that depression of in vitro lymphocyte histogenesis in the cattle persistently infected with bvd virus is not attributable to decreased production of interleukin-2.

Free access
in American Journal of Veterinary Research

SUMMARY

Recombinant human interleukin-2 (rhil-2) was evaluated for its influence on total and differential wbc counts, lymphocyte blastogenic responsiveness to mitogens, and several measurements of neutrophil function in clinically normal and in dexamethasone-treated cattle. A single dose of rhil-2 (2.5 × 107 U) given sc had no influence on the total or differential wbc count; however, it did cause an inhibition of neutrophil random migration. The other measurements of neutrophil function (Staphylococcus aureus ingestion, cytochrome C reduction, iodination, and antibody-dependent and antibody-independent cell-mediated cytotoxicity) evaluated were not significantly altered. The rhil-2 treatment was associated with a significant (P < 0.01) decrease in uptake of [3H]thymidine in unstimulated lymphocytes and a tendency toward enhanced blastogenesis of lymphocytes stimulated with phytohemagglutinin. This enhancement was significant (P < 0.05) only when the results were expressed as a stimulation index. Lymphocyte responsiveness to concanavalin A and pokeweed mitogen was not significantly influenced by rhil-2 administration. Dexamethasone (0.04 mg/kg) administered every 24 hours for 3 consecutive days altered the wbc count and several measurements of lymphocyte and neutrophil function. The administration of a single dose of rhil-2 (2.5 × 107 U) 8 hours after the first dose of dexamethasone did not alter the influence of dexamethasone on any of the measurements. These results indicated that rhil-2 has some biologic activity in cattle, but when used as administered here, did not overcome the influence of dexamethasone on the in vitro measurements of lymphocyte and neutrophil function that were evaluated.

Free access
in American Journal of Veterinary Research