Effect of therapeutic doses of enrofloxacin on circulating lymphocyte subpopulations in pigs

Twenty pigs of similar genetics (PIC) were used. Pigs were randomly divided into two groups: experimental (ENRO, n = 10) and control (C, n = 10). From day 0 to day 4, pigs from ENRO group received enrofloxacin at the recommended therapeutic dose. Pigs from C group received PBS instead of enrofloxacin. Blood samples were collected on days 0 (before antibiotic administration), 2, 4 (during antibiotic therapy), 9, and 13 of the study (after enrofloxacin administration). Haematological examination and flow cytometry were used to establish the relative and absolute counts of various leukocyte subsets. Lymphocyte subpopulations were measured by fluorochrom-labelled antibodies according to following definitions: CD3+ (T cells), CD21+ (B cells), CD4+CD8- (helper T cells, Th), CD4-CD8+ (cytolytic T cells, CLT), CD4+CD8+ (cytolytic and memory T cells). The present study revealed the modulating effect of enrofloxacin on the composition of circulating lymphocytes in pigs. Concentration and percentage of CD8+ cells decreased significantly after treatment with enrofloxacin and as a result the absolute CD4/CD8 ratio increased significantly as compared to control group (P < 0.05).These findings should prompt further studies on the practical significance of the results obtained in terms of clinical implications. In view of the results, it cannot be excluded that enrofloxacin may also have immunomodulatory effects on host response to infection.