Antibody-Fab and -Fc features promote Mycobacterium tuberculosis restriction

Abstract

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), a leading cause of death by an infectious disease globally, has no efficacious vaccine. Antibodies are implicated in M. tuberculosis control, but the mechanisms of action remain poorly understood. We assembled a library of monoclonal antibodies (mAb) and screened for M. tuberculosis-restrictive activity in mice, identifying protective antibodies targeting diverse antigens. To dissect the mechanism of mAb-mediated M. tuberculosis restriction, we optimized a protective lipoarabinomannan-specific mAb, generating Fc variants. In vivo analysis of these Fc variants revealed a role for Fc-effector function in M. tuberculosis restriction. Restrictive Fc variants altered distribution of M. tuberculosis across innate immune cells. Single-cell transcriptomics highlighted distinctly activated pathways within innate immune cell subpopulations, identifying early activation of neutrophils as a key signature of mAb-mediated M. tuberculosis restriction. Therefore, antibody-mediated restriction of M. tuberculosis is associated with reorganization of the tissue-level immune response to infection and depends on the collaboration of antibody Fab and Fc.