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Antigen-specific CD4 and CD8 T cells are important components of the immune response to Mycobacterium tuberculosis, yet little information is currently known regarding how the breadth, specificity, phenotype, and function of M. tuberculosis-specific T cells correlate with M. tuberculosis infection outcome in humans. To facilitate evaluation of human M. tuberculosis-specific T cell responses targeting multiple different Ags, we sought to develop a high throughput and reproducible T cell response spectrum assay requiring low blood sample volumes. We describe here the optimization and standardization of a microtiter plate-based, diluted whole blood stimulation assay utilizing overlapping peptide pools corresponding to a functionally diverse panel of 60 M. tuberculosis Ags. Using IFN-γ production as a readout of Ag specificity, the assay can be conducted using 50 μl of blood per test condition and can be expanded to accommodate additional Ags. We evaluated the intra- and interassay variability, and implemented testing of the assay in diverse cohorts of M. tuberculosis-unexposed healthy adults, foreign-born adults with latent M. tuberculosis infection residing in the United States, and tuberculosis household contacts with latent M. tuberculosis infection in a tuberculosis-endemic setting in Kenya. The M. tuberculosis-specific T cell response spectrum assay further enhances the immunological toolkit available for evaluating M. tuberculosis-specific T cell responses across different states of M. tuberculosis infection, and can be readily implemented in resource-limited settings. Moreover, application of the assay to longitudinal cohorts will facilitate evaluation of treatment- or vaccine-induced changes in the breadth and specificity of Ag-specific T cell responses, as well as identification of M. tuberculosis-specific T cell responses associated with M. tuberculosis infection outcomes.

Background: Rifampin-resistant tuberculosis is a leading cause of morbidity worldwide; only one-third of persons start treatment, and outcomes are often inadequate. Several trials demonstrate 90% efficacy using an all-oral, 6-month regimen of bedaquiline, pretomanid, and linezolid (BPaL), but significant toxicity occurred using 1200-mg linezolid. After US Food and Drug Administration approval in 2019, some US clinicians rapidly implemented BPaL using an initial 600-mg linezolid dose adjusted by serum drug concentrations and clinical monitoring., Methods: Data from US patients treated with BPaL between 14 October 2019 and 30 April 2022 were compiled and analyzed by the BPaL Implementation Group (BIG), including baseline examination and laboratory, electrocardiographic, and clinical monitoring throughout treatment and follow-up. Linezolid dosing and clinical management was provider driven, and most patients had linezolid adjusted by therapeutic drug monitoring., Results: Of 70 patients starting BPaL, 2 changed to rifampin-based therapy, 68 (97.1%) completed BPaL, and 2 of the 68 (2.9%) experienced relapse after completion. Using an initial 600-mg linezolid dose daily adjusted by therapeutic drug monitoring and careful clinical and laboratory monitoring for adverse effects, supportive care, and expert consultation throughout BPaL treatment, 3 patients (4.4%) with hematologic toxicity and 4 (5.9%) with neurotoxicity required a change in linezolid dose or frequency. The median BPaL duration was 6 months., Conclusions: BPaL has transformed treatment for rifampin-resistant or intolerant tuberculosis. In this cohort, effective treatment required less than half the duration recommended in 2019 US guidelines for drug-resistant tuberculosis. Use of individualized linezolid dosing and monitoring likely enhanced safety and treatment completion. The BIG cohort demonstrates that early implementation of new tuberculosis treatments in the United States is feasible., Competing Interests: Potential conflicts of interest. C. A. H. reports honoraria from the Infectious Diseases Society of America for an IDWeek 2022 presentation, travel support from the University of Employer, and Pfizer stock ownership. M. C. S. reports grants from the National Institute of Minority Health and Health Disparities (R21MD017943-01; Neighborhood transportation vulnerability and geographic patterns of diabetes-related limb loss) and the American Diabetes Association (Diabetic Ulcer Computational Sensing System), paid to the institution, and payment from the Society for Advancement in Wound Care for speaking at the 2023 spring meeting. D. A. reports a grant from the Centers for Disease Control and Prevention (CDC) as the primary investigator of TB Centers of Excellence, travel support from the CDC, and participation in the CDC's Tuberculosis Trials Consortium data and safety monitoring board. L. C. reports grants from USAID (federal award to institution for global research capacity building) and the California Department of Public Health (training award to institution for pandemic response); an unpaid position as president of the Executive Leadership Board for the North American Region Union Against Tuberculosis and Lung Diseases; and an unpaid position on the coordinating board of STOP TB USA. M. B. D reports institutional contracts with the CDC and Westat. A. V. E. reports travel support for meetings from the CDC. K. A. R. reports grants and travel support from the CDC’s Division of TB Elimination and a position as the liaison for the National Association of County and City Health Officials to the Advisory Committee for the Elimination of Tuberculosis. M. C. R. reports travel support for meeting from Association of Public Health Laboratories (APHL) and positions as chair of the APHL Infectious Diseases Committee and member of the APHL Tuberculosis Subcommittee and the College of American Pathologists Microbiology Committee. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)