Comparative phenotypic profile of subpopulations of peripheral blood leukocytes in European (Bos taurus taurus) and Zebu cattle (Bos taurus indicus).

Differences in cellular and humoral immunity in Zebu (Bos taurus indicus) and European (B. taurus taurus) cattle breeds, which may be related to differences in resistance or susceptibility to infectious or parasitic diseases, are largely unknown. This study aimed to perform a comparative analysis of innate and adaptive immunity of European (including Holstein, Brown Swiss, and Hereford) and Zebu (including Gir, Nelore, and Guzera) breeds, by assessing their peripheral blood leukocyte profiles (i.e., monocytes, eosinophils, and lymphocytes, including CD4(+) and CD8(+) T cells, and CD21(+) B cells). Higher frequencies of cells involved in innate immunity were observed in Zebu breeds, particularly monocytes and non-T and non-B cells (13.37 ± 0.9058 and 37.67 ± 1.55, respectively). This finding may contribute to the increased resistance of B. taurus indicus to certain infectious and parasitic diseases. Considering other leukocyte populations in the peripheral blood, among-breed variation was greater than differences between the two subspecies. This study will serve as a basis for further investigations regarding comparative immunology and resistance to infectious and parasitic diseases of cattle.

Immune response of bovines stimulated by synthetic vaccine SBm7462 against Rhipicephalus (Boophilus) microplus.

Ten-month-old calves Bos taurus taurus were immunized with three doses of SBm7462 with saponin as an adjuvant at 30-day intervals and were evaluated for IgG isotypes, phenotype circulating lymphocytes and changes in the lymph nodes (LN). SBm7462 stimulated the production of predominantly IgG1-isotype IgG antibodies. The lymph nodes exhibited activation at the seventh day after the first immunization, with areas of paracortical and interfollicular hyperplasia and the early formation of germinal centers (GC). Fifteen days after the first immunization, the GC exhibited compartmentalization of cellular populations, a light zone (LZ), a dark zone (DZ) and a mantle. At the same time, hyperplasia of the medullary cords was observed with cells associating with DC cells. Seven days after the first immunization, apoptosis in the DZ and in the paracortical region became evident. By day 15, there was an increase in the medullary cords, which became more numerous at days 35 and 42. PAP-positive cells were found in the paracortical region, medullary cords and GC 7 days after the first immunization. At day 35, there were further strongly PAP-positive cells in the medullary cords. By comparison, none of these changes were observed in the lymph nodes of control groups at any of the days analyzed. The number of CD21(+) lymphocytes increased in the immunized groups after the first inoculation, with a maximum number observed at 15 and 10 days after the first and third immunizations, respectively. Compared to pre-immunization counts, the percentage of WC1(+) gammadelta T-lymphocytes displayed more variation, increasing 5 days after the second immunization but decreasing over the following days. According to the results, the synthetic anti Rhipicephalus microplus vaccine elicits a complete immune response being T-dependant.

Activation/modulation of adaptive immunity emerges simultaneously after 17DD yellow fever first-time vaccination: is this the key to prevent severe adverse reactions following immunization?

Over past decades the 17DD yellow fever vaccine has proved to be effective in controlling yellow fever and promises to be a vaccine vector for other diseases, but the cellular and molecular mechanisms by which it elicits such broad-based immunity are still unclear. In this study we describe a detailed phenotypic investigation of major and minor peripheral blood lymphocyte subpopulations aimed at characterizing the kinetics of the adaptive immune response following primary 17DD vaccination. Our major finding is a decreased frequency of circulating CD19+ cells at day 7 followed by emerging activation/modulation phenotypic features (CD19+interleukin(IL)10R+/CD19+CD32+) at day 15. Increased frequency of CD4+human leucocyte antigen D-related(HLA-DR+) at day 7 and CD8+HLA-DR+ at day 30 suggest distinct kinetics of T cell activation, with CD4+ T cells being activated early and CD8+ T cells representing a later event following 17DD vaccination. Up-regulation of modulatory features on CD4+ and CD8+ cells at day 15 seems to be the key event leading to lower frequency of CD38+ T cells at day 30. Taken together, our findings demonstrate the co-existence of phenotypic features associated with activation events and modulatory pathways. Positive correlations between CD4+HLA-DR+ cells and CD4+CD25high regulatory T cells and the association between the type 0 chemokine receptor CCR2 and the activation status of CD4+ and CD8+ cells further support this hypothesis. We hypothesize that this controlled microenviroment seems to be the key to prevent the development of serious adverse events, and even deaths, associated with the 17DD vaccine reported in the literature.

Perfil fenotípico de linfócitos periféricos de bovinos de raças européias / Phenotypic profile of peripheral blood lymphocytes from European bovines

The phenotypic profile of bovine lymphocytes was evaluated in 18 bovines (Bos taurus) from three different breeds, being nine Holstein, six Hereford, and three Brown Swiss. All animals were free from ticks and hemoparasites, as determined after jugular vein blood sampling. The immunophenotypes of peripheral lymphocytes were evaluated by flow cytometry. Peripheral lymphocytes were exposed to bovine fluorescein-labeled monoclonal antibodies including anti-CD4, anti-CD8, and anti-purified bovine CD21 specificities. After lysing the erythrocytes with a commercial lysing solution (FACS TM ), the lymphocytes were washed, fixed, and evaluated by flow cytometry. Significant differences in the phenotypic profiles of peripheral lymphocytes among all breeds were found. Holstein animals showed a lower percentage of total T lymphocytes (CD4 and CD8) and higher percentage of B lymphocytes (CD21). In addition, the lymphocytes from Holstein animals showed a lower T/B ratio than the lymphocytes from Hereford animals. These results suggest the existence of different phenotypic profiles of peripheral lymphocytes from European breeds of cattle. Such differences may be related to the different pattern of immune response described for these breeds in the literature and may account to varying disease resistance among breeds.