Ag 85 A-specific CD 4 T cell lines derived after boosting BCG-vaccinated cattle with Ad 585 A possess both mycobacterial growth inhibition and anti-inflammatory properties

There is a need to improve the efficacy of the BCG vaccine against human and bovine tuberculosis. Previous data showed that boosting bacilli Calmette-Guerin (BCG)-vaccinated cattle with a recombinant attenuated human type 5 adenovirally vectored subunit vaccine (Ad5-85A) increased BCG protection and was associated with increased frequency of Ag85A-specific CD4 T cells post-boosting. Here, the capacity of Ag85A-specific CD4 T cell lines – derived before and after viral boosting – to interact with BCGinfected macrophages was evaluated. No difference before and after boosting was found in the capacity of these Ag85A-specific CD4 T cell lines to restrict mycobacterial growth, but the secretion of IL-10 in vitro post-boost increased significantly. Furthermore, cell lines derived post-boost had no statistically significant difference in the secretion of pro-inflammatory cytokines (IL-1b, IL-12, IFNc or TNFa) compared to pre-boost lines. In conclusion, the protection associated with the increased number of Ag85Aspecific CD4 T cells restricting mycobacterial growth may be associated with anti-inflammatory properties to limit immune-pathology. 2018 Department for Environment Food and Rural Affairs. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).