Effect of dietary restriction on cell-mediated immune responses in cattle infected with Mycobacterium bovis

The effects of a single injection of dexamethasone-21-isonicotinate on the lymphocyte functions of dairy cows at two weeks post partum

“…Our findings are in accordance with the investigations of Burton and Kehrli [8] who demonstrated that the percentages of CD2 + , CD4 + and CD8 + T cells are not altered by 0.04 mg/kg/ day dexamethasone administered to young bulls on three consecutive days. However, in other studies glucocorticosteroids have been shown to cause lymphopenia and alterations of lymphocyte subsets [2,14,16,42]. Thus, the differences between the results of previous studies and the present one can mainly be explained by the differences in the sort of corticosteroids administered as well as differences in the age of the probands, the dosage regimen and the number of treatments.…”

“…In practice, the use of glucocorticosteroids in postpartum cows, however, is limited since a great number of veterinarians share the common perception that these drugs are contraindicated due to their potential to induce immunosuppression. Reports on the immunomodulating capacities of glucocorticosteroids, however, include a wide variety of preparations, dosages, numbers of treatments and routes of administration [2,8,14,16,27]. Glucocorticosteroids have been shown to cause leukocytosis involving neutrophilia and lymphopenia [36], suppression of leukocyte blastogenesis [26,30,33] and to change T-lymphocyte subpopulation patterns [2,8,16].…”

“…Reports on the immunomodulating capacities of glucocorticosteroids, however, include a wide variety of preparations, dosages, numbers of treatments and routes of administration [2,8,14,16,27]. Glucocorticosteroids have been shown to cause leukocytosis involving neutrophilia and lymphopenia [36], suppression of leukocyte blastogenesis [26,30,33] and to change T-lymphocyte subpopulation patterns [2,8,16]. The increase in the number of circulating neutrophils following the administration of glucocorticosteroids has been well explained by the down-regulation of L-selectin and adhesion molecules of the β2-integrin family on these cells, resulting in an impaired ability of neutrophils to leave the circulation [9,23].…”

“…Oldham and Howard [27] have shown that daily intramuscular injections of dexamethasone at a dosage of 0.5 mg/kg/ day in calves for 20 days results in neutrophilia and lymphopenia with a significant reduction in the number of CD2 + T cells without apparent differences in CD4 + and CD8 + subpopulations. Moreover, a single intramuscular injection of 0.2 mg/kg dexamethasone induced lymphopenia associated with decreased numbers of circulating CD2 + and CD4 + T cells without changes in the number of circulating CD8 + T cell populations in cows [16]. These changes in the number of circulating lymphocytes and lymphocyte subsets are thought to be the effects of glucocorticosteroid on the expression of lymphocyte adhesion molecules that mediate cell-cell interactions and leukocyte extravasation.…”

Assessment of diagnostic tools for eradication of bovine tuberculosis in cattle co-infected withMycobacterium bovisandM. aviumsubsp.paratuberculosis

“…Some factors have been associated with the failure of these eradication campaigns. Firstly, the performance of the tuberculin tests could be affected by factors inherent to the method [19], or factors that have been described to impair the immune response, such as treatment with corticoids and the effect of stress [7,12]. Secondly, some wildlife species have been blamed for acting as a reservoir.…”