Segregation of Mechanisms for Cytotoxic T Lymphocyte Killing between Lungs and Regional Lymph Nodes Subsequent to Intratracheal Delivery of Adenovirus 2 Vector

Recombinant adenovirus (Ad) vectors, highly effective for targeting the respiratory epithelium, have been investigated for proposed application in mucosal immunization. For rendering successful use of Ad vectors, it is imperative to understand the host immune responses in affected organs. We investigated the mechanisms of cytotoxic T lymphocyte (CTL) killing following intratracheal instillation with recombinant Ad2/betagal-2 vector. From the analysis of CTL responses, it became apparent that the lung CTLs were more Fas-dependent, whereas pulmonary lymph nodes (LN) and splenic CTLs were more perforin-dependent. Although there was a segregation in the mode of CTL killing, both mechanisms of cytolysis were used in the described tissues, and the observed dominance in CTL killing was maintained irrespective of the target evaluated. Restimulation of LN and spleen cells did not change dominance in the CTL mechanism utilized. Absence or blockage of perforin or Fas did not result in reciprocal compensation by the other effector mechanism except in Fas ligand-deficient LN and spleens. In vitro restimulation of immune lymphocytes from each mouse group tested showed segregation in the types of cytokines generated. Ad2-restimulated cells showed bias toward IL-2 and IFN-gamma, while betagal-restimulated cells showed bias toward IL-4 and IL-10.