title: Antigen-specific secretion of IFNγ and CXCL10 in whole blood assay detects Mycobacterium leprae infection but does not discriminate asymptomatic infection from symptomatic leprosy.
abstract: To advance toward a whole blood assay (WBA)-based test capable of facilitating the diagnosis of paucibacillary (PB) leprosy, we evaluated a prototype in-tube WBA using combinations of Mycobacterium leprae antigens. Blood was collected from newly diagnosed untreated PB (n=38), multibacillary (MB) (n=30), healthy household contacts (HHC) of MB (n=27), and endemic controls (n=61) residing in Goiânia and Fortaleza, Brazil. Blood was incubated with M. leprae cell sonicate, recombinant proteins (46f+LID-1; ML0276+LID-1), or controls (phosphate-buffered saline, phytohemagglutinin, M. tuberculosis purified protein derivative). Antigen-specific IFNγ production was observed in 71-84% and 55% of PB and HHC, respectively. Antigen-specific CXCL10 levels were similarly assessed to determine if, unlike IFNγ, CXCL10 could differentiate PB from HHC with repeated exposure/asymptomatic M. leprae infection. The CXCL10 levels induced in response to M. leprae antigens could not, however, differentiate PB from HHC. Despite these limitations, the WBAs reported here still represent important tools for assessing M. leprae infection rates and evaluating the impact of control measures.
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, GO 74605-020, Brazil.
authors.forename: Emerith Mayra
authors.initials: EM
authors.lastname: Hungria
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, GO 74605-020, Brazil.
authors.forename: Aline Araújo
authors.initials: AA
authors.lastname: Freitas
authors.affiliation: Centro de Dermatologia Dona Libânia, Fortaleza, CE 60035-100, Brazil.
authors.forename: Maria Araci Andrade
authors.initials: MA
authors.lastname: Pontes
authors.affiliation: Centro de Dermatologia Dona Libânia, Fortaleza, CE 60035-100, Brazil.
authors.forename: Heitor Sá
authors.initials: HS
authors.lastname: Gonçalves
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, GO 74605-020, Brazil.
authors.forename: Ana Lúcia Osório Maroccolo
authors.initials: AL
authors.lastname: Sousa
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, GO 74605-020, Brazil.
authors.forename: Maurício Barcelos
authors.initials: MB
authors.lastname: Costa
authors.affiliation: Hospital de Doenças Tropicais/Dr Anuar Auad, Goiânia, GO 74605-020, Brazil.
authors.forename: Mirian Lane Oliveira Rodrigues
authors.initials: ML
authors.lastname: Castilho
authors.affiliation: Infectious Disease Research Institute, Seattle, WA 98102, USA.
authors.forename: Malcolm S
authors.initials: MS
authors.lastname: Duthie
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, GO 74605-020, Brazil. Electronic address: mmastefani@gmail.com.
authors.forename: Mariane Martins Araújo
authors.initials: MM
authors.lastname: Stefani
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology*; D058345:Asymptomatic Infections / Q000453:epidemiology*; D001681:Biological Assay / Q000379:methods; D001938:Brazil; D054357:Chemokine CXCL10 / Q000276:immunology*; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000276:immunology*; D056005:Leprosy, Paucibacillary / Q000097:blood / Q000175:diagnosis / Q000276:immunology* / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D009166:Mycobacterium leprae / Q000276:immunology*; D009169:Mycobacterium tuberculosis / Q000276:immunology; D011994:Recombinant Proteins / Q000276:immunology; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D054357:Chemokine CXCL10; D011994:Recombinant Proteins; D007371:Interferon-gamma
keywords: CXCL10; Cell-mediated immunity; Diagnosis; IFNγ; Leprosy; Whole blood assay