IFN-γ- GranzymeB + Natural killer cells are induced by IV BCG vaccination and associated with protection against tuberculosis in rhesus macaques

Mohau S. Makatsa, Emma Bishop, Allison N. Bucsan, Matthew Sutton, Chelsea Lehman, Molly Robertson, Krystle K.Q. Yu, Joshua M. Peters, Bryan D. Bryson, Mario Roederer, Robert A. Seder, Patricia A. Darrah, Chetan Seshadri

DOI: https://doi.org/10.1016/j.mucimm.2025.10.011

Abstract: Intravenous (IV) vaccination with Bacillus Calmette–Guerin (BCG) mediates sterilizing immunity against Mycobacterium tuberculosis (Mtb) in rhesus macaques but the cellular mechanisms underlying protection are undefined. We used mass cytometry (CyTOF) to broadly profile pulmonary immunity induced by IV BCG and observed an expansion of CD69- NK cells characterized by expression of the cytotoxic molecule granzyme B but not IFN-γ in bronchoalveolar lavage. Flow cytometry experiments revealed that CD69- NK cell frequencies are increased in the lungs after IV BCG and associated with protection against Mtb challenge. An in vitro cytotoxicity assay revealed superior cytolytic capacity of CD69- NK cells compared to CD69 + NK cells derived from the lungs of IV BCG vaccinated macaques. Taken together, our data suggest that IV BCG induces the recruitment of CD69-granzyme B + NK cells to the lungs where they may contribute to protection via direct lysis of Mtb-infected cells.

One Sentence Summary: Intravenous BCG vaccination induces the expansion of CD69- NK cells, which display enhanced cytotoxicity in-vitro and is associated with protection against tuberculosis.