AUTHOR=Ruiz-Tagle Cinthya , Naves Rodrigo , García Patricia , Günther Anna , Schneiderhan-Marra Nicole , Balcells María Elvira 

TITLE=Differential levels of anti-Mycobacterium tuberculosis-specific IgAs in saliva of household contacts with latent tuberculosis infection

JOURNAL=Frontiers in Medicine

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2023.1267670

DOI=10.3389/fmed.2023.1267670

ISSN=2296-858X

ABSTRACT=<sec><title>Introduction</title><p>Mucosal immunity is strongly elicited in early stages of many respiratory and enteric infections; however, its role in tuberculosis pathogenesis has been scarcely explored. We aimed to investigate <italic>Mycobacterium tuberculosis</italic> (Mtb) specific IgA levels in saliva in different stages of latent Tuberculosis Infection (TBI).</p></sec><sec><title>Methodology</title><p>A multiplex bead-based Luminex immunoassay was developed to detect specific IgA against 12 highly immunogenic Mtb antigens. A prospective cohort of household contacts (&gt;14 years) of pulmonary TB cases was established in Santiago, Chile. Contacts were classified as Mtb-infected or not depending on serial interferon-γ release assay results. Saliva samples were collected and tested at baseline and at a 12-week follow-up.</p></sec><sec><title>Results</title><p>Mtb-specific IgA was detectable at all visits in all participants (<italic>n</italic> = 168), including the “non-Mtb infected” (<italic>n</italic> = 64). Significantly higher median levels of IgA were found in the “Mtb infected” compared to the uninfected for anti-lipoarabinomannan (LAM) (110 vs. 84.8 arbitrary units (AU), <italic>p</italic> &lt; 0.001), anti-PstS1 (117 vs. 83 AU, <italic>p</italic> &lt; 0.001), anti-Cell Membrane Fraction (CMF) (140 vs. 103 AU, <italic>p</italic> &lt; 0.001) and anti-Culture Filtrate Proteins (CFP) (median 125 vs. 96 AU, <italic>p</italic> &lt; 0.001), respectively. Nonetheless, the discriminatory performance of these specific mucosal IgA for TBI diagnosis was low.</p></sec><sec><title>Conclusion</title><p>Saliva holds Mtb-specific IgA against several antigens with increased levels for anti-LAM, anti-PstS1, anti-CMF and anti-CFP found in household contacts with an established TBI. The role of these mucosal antibodies in TB pathogenesis, and their kinetics in different stages of Mtb infection merits further exploring.</p></sec>