T Cells Specific for a Mycobacterial Glycolipid Expand after Intravenous Bacillus Calmette-Guérin Vaccination.

Erik D Layton,Adriaan J Minnaard,Soumik Barman,Malisa T Smith,Robert A Seder,Chetan Seshadri,Nabil Tahiri,Damien B Wilburn,John D Altman,Krystle K Q Yu,Patricia A Darrah,Thomas J Scriba,Mario Roederer

doi:10.4049/jimmunol.2001065

Abstract

Intradermal vaccination with Mycobacterium bovis bacillus Calmette-Guérin (BCG) protects infants from disseminated tuberculosis, and i.v. BCG protects nonhuman primates (NHP) against pulmonary and extrapulmonary tuberculosis. In humans and NHP, protection is thought to be mediated by T cells, which typically recognize bacterial peptide Ags bound to MHC proteins. However, during vertebrate evolution, T cells acquired the capacity to recognize lipid Ags bound to CD1a, CD1b, and CD1c proteins expressed on APCs. It is unknown whether BCG induces T cell immunity to mycobacterial lipids and whether CD1-restricted T cells are resident in the lung. In this study, we developed and validated Macaca mulatta (Mamu) CD1b and CD1c tetramers to probe ex vivo phenotypes and functions of T cells specific for glucose monomycolate (GMM), an immunodominant mycobacterial lipid Ag. We discovered that CD1b and CD1c present GMM to T cells in both humans and NHP. We show that GMM-specific T cells are expanded in rhesus macaque blood 4 wk after i.v. BCG, which has been shown to protect NHP with near-sterilizing efficacy upon M. tuberculosis challenge. After vaccination, these T cells are detected at high frequency within bronchoalveolar fluid and express CD69 and CD103, markers associated with resident memory T cells. Thus, our data expand the repertoire of T cells known to be induced by whole cell mycobacterial vaccines, such as BCG, and show that lipid Ag-specific T cells are resident in the lungs, where they may contribute to protective immunity.

Highlights

This allowed us to use H. sapiens CD1d tetramer loaded with a-GalCer to study the molecular mechanisms of Ag recognition by invariant NKT (iNKT) cells in rhesus macaques [35]
We developed and validated Macaca mulatta (Mamu) CD1bGMM and Mamu CD1c-glucose monomycolate (GMM) tetramers, establishing the nonhuman primates (NHP) as a natural animal model in which to study the phenotypes and functions of CD1-reactive T cells in health and disease. We discovered that both CD1b and CD1c can present GMM to T cells in humans and NHP, providing a potential mechanism for how primates evolved the capacity to discriminate among Ags with identical head groups but various lipid chain lengths
bacillus Calmette–Guerin (BCG) leads to the expansion of GMMspecific T cells in the blood, which are detectable in bronchoalveolar lavage (BAL) fluid, suggesting that lipid Ag-specific T cells may contribute to the protective immune response to M. tuberculosis

Summary

Introduction

We generated Mamu CD1b and Mamu CD1c tetramers and validated their ability to detect GMM-specific T cells by sorting them from the blood of BCG-vaccinated animals and performing in vitro expansion and functional assays. Mamu CD1b-GMM tetramer stained 0.1% of T cells in PBMC of a BCG-vaccinated rhesus macaque compared with a mock-loaded control tetramer (Fig. 1D).

Results

Conclusion