Introduction: The aim of the study was to explore the effect of enrofloxacin on production of selected cytokines by porcine peripheral blood mononuclear cells (PBMCs).Material and Methods: Twenty pigs (10 control and 10 experimental) were used in this research. Pigs from experimental group received enrofloxacin at therapeutic doses. Blood samples were collected before, during, and after treatment with enrofloxacin. PBMCs were incubated with or without lipopolysaccharide (LPS). Production of IL-6, IL-10, INF-γ, and TNF-α were determined by ELISA.Results: Administration of enrofloxacin to healthy pigs for 5 d induced a transient reduction of the PBMCs response to LPS in terms of IL-6 and TNF-α secretion. The concentration of IL-6 returned to the day 0 level shortly after treatment, while TNF-α production remained reduced for 10 d after the treatment. The production of IL-10 was not affected by enrofloxacin. The level of IFN-γ was below the detection limit of the tests.Conclusion: The results indicate that enrofloxacin administered in vivo in therapeutic doses has an immunomodulatory effect through its capacity to inhibit secretion of IL-6 and TNF-α by porcine PBMC stimulated by LPS.

Introduction: The aim of the study was to evaluate the effect of administration of therapeutic doses of ceftiofur and tulathromycin on the circulating lymphocyte subpopulations in healthy pigs. Material and Methods: The study was conducted on thirty healthy 7- to 10-week-old pigs, assigned to three groups: the TUL group, injected with tulathromycin (n = 10); the CEF group, injected with ceftiofur (n = 10); and the C group, the control with no antibiotic administration (n = 10). Blood samples were collected before, during, and after treatment with antimicrobials. Lymphocyte subpopulations circulating in the blood were determined by immunostaining and flow cytometry analyses. Results: Following administration of a therapeutic dose of tulathromycin, there were no changes in the lymphocyte subpopulations circulating in blood. In contrast, administration of ceftiofur at the recommended dose decreased the absolute number of CD3+, CD21+, CD4+CD8-, CD4-CD8+, and double positive CD4CD8 cells. Conclusion: Results from the study indicate that ceftiofur possesses the ability to modulate the immune system in healthy pigs by decreasing lymphocyte subpopulations circulating in blood.