T lymphocytes subsets and cytokine pattern induced by vaccination against bovine brucellosis employing S19 calfhood vaccination and adult RB51 revaccination

The aims of this study were to address the protective immune response induced by S19 vaccination (n = 10) and RB51 revaccination, in pregnant (n = 9) and non-pregnant (n = 10) S19 calfhood-vaccinated cattle as follows: evaluate the in vitro CD4+ and CD8+ T-lymphocytes specific proliferation, and in vitro expression of IFN-γ by CD4+ and CD8+ T-cells and IL-4 by CD4+, CD8+ and CD21+ lymphocytes subset. Upon in vitro stimulation with γ-irradiated Brucella abortus 2308, blood mononuclear cells from S19 vaccinated and RB51 revaccinated cows exhibited significantly higher proliferation of CD4+ and CD8+ T-lymphocytes and CD4+IFN-γ+ T-cells compared to non-vaccinated animals. RB51 revaccination, regardless of the pregnancy status, did not enhance the proliferation of CD4+ or CD8+ T-cells nor IFN-γ or IL-4 production. Data from the present study suggest that cattle's cellular immune response induced after brucellosis vaccination and revaccination is due to CD4+ and CD8+ T-lymphocytes, being CD4+ T-cells the main source of IFN-γ.