Recall responses in the lung environment are impacted by age in a pilot study of Mycobacterium bovis-BCG vaccinated rhesus macaques.

Age-related changes in the immune system increase susceptibility to infectious diseases. Vaccines are an important tool to prevent infection or boost immunological memory; however, vaccines are less effective in aged individuals. In order to protect our aging population from the threat of infectious diseases, we must gain a better understanding of age-related alterations in the immune response at the site of infection. The lung is one site of frequent infection in older individuals. In this study, we expanded on our previous work to study vaccine-induced immune responses in the local lung environment in a pilot study of aged rhesus macaques. To do this, we developed an in vivo model to probe recall responses to tuberculin challenge in the lungs 8 weeks and 16 weeks post-Mycobacterium bovis BCG vaccination by performing targeted bronchoalveolar lavages. In parallel, we determined peripheral blood responses in vaccinated animals to compare systemic and local tissue responses to tuberculin challenge. We found that following lung tuberculin challenge 8 weeks post-vaccination, aged animals had reduced T cell responses, particularly within the CD8