title: Combinatorial Immunoprofiling in Latent Tuberculosis Infection. Toward Better Risk Stratification.
abstract: BACKGROUND
  Most immunocompetent patients diagnosed with latent tuberculosis infection (LTBI) will not progress to tuberculosis (TB) reactivation. However, current diagnostic tools cannot reliably distinguish nonprogressing from progressing patients a priori, and thus LTBI therapy must be prescribed with suboptimal patient specificity. We hypothesized that LTBI diagnostics could be improved by generating immunomarker profiles capable of categorizing distinct patient subsets by a combinatorial immunoassay approach.
  
  
  OBJECTIVE
  A combinatorial immunoassay analysis was applied to identify potential immunomarker combinations that distinguish among unexposed subjects, untreated patients with LTBI, and treated patients with LTBI and to differentiate risk of reactivation.
  
  
  METHODS
  IFN-γ release assay (IGRA) was combined with a flow cytometric assay that detects induction of CD25(+)CD134(+) coexpression on TB antigen-stimulated T cells from peripheral blood. The combinatorial immunoassay analysis was based on receiver operating characteristic curves, technical cut-offs, 95% bivariate normal density ellipse prediction, and statistical analysis. Risk of reactivation was estimated with a prediction formula.
  
  
  RESULTS
  Sixty-five out of 150 subjects were included. The combinatorial immunoassay approach identified at least four different T-cell subsets. The representation of these immune phenotypes was more heterogeneous in untreated patients with LTBI than in treated patients with LTBI or unexposed groups. Patients with IGRA(+) CD4(+)CD25(+)CD134(+) T-cell phenotypes had the highest estimated reactivation risk (4.11 ± 2.11%).
  
  
  CONCLUSIONS
  These findings suggest that immune phenotypes defined by combinatorial assays may potentially have a role in identifying those at risk of developing TB; this potential role is supported by risk of reactivation modeling. Prospective studies will be needed to test this novel approach.
authors.affiliation: 1 Division of Pulmonary and Critical Care Medicine, Department of Medicine.|2 Public Health Department, Olmsted County Tuberculosis Clinic, Rochester, Minnesota; and.|3 Mayo Clinic Center for Tuberculosis, Rochester, Minnesota.
authors.forename: Patricio
authors.initials: P
authors.lastname: Escalante
authors.affiliation: 1 Division of Pulmonary and Critical Care Medicine, Department of Medicine.|4 Department of Immunology, and.
authors.forename: Tobias
authors.initials: T
authors.lastname: Peikert
authors.affiliation: 4 Department of Immunology, and.
authors.forename: Virginia P
authors.initials: VP
authors.lastname: Van Keulen
authors.affiliation: 4 Department of Immunology, and.
authors.forename: Courtney L
authors.initials: CL
authors.lastname: Erskine
authors.affiliation: 1 Division of Pulmonary and Critical Care Medicine, Department of Medicine.
authors.forename: Cathy L
authors.initials: CL
authors.lastname: Bornhorst
authors.affiliation: 1 Division of Pulmonary and Critical Care Medicine, Department of Medicine.
authors.forename: Boleyn R
authors.initials: BR
authors.lastname: Andrist
authors.affiliation: 2 Public Health Department, Olmsted County Tuberculosis Clinic, Rochester, Minnesota; and.|3 Mayo Clinic Center for Tuberculosis, Rochester, Minnesota.
authors.forename: Kevin
authors.initials: K
authors.lastname: McCoy
authors.affiliation: 4 Department of Immunology, and.
authors.forename: Larry R
authors.initials: LR
authors.lastname: Pease
authors.affiliation: 5 Department of Laboratory Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Roshini S
authors.initials: RS
authors.lastname: Abraham
authors.affiliation: 4 Department of Immunology, and.
authors.forename: Keith L
authors.initials: KL
authors.lastname: Knutson
authors.affiliation: 4 Department of Immunology, and.
authors.forename: Hirohito
authors.initials: H
authors.lastname: Kita
authors.affiliation: 4 Department of Immunology, and.
authors.forename: Adam G
authors.initials: AG
authors.lastname: Schrum
authors.affiliation: 1 Division of Pulmonary and Critical Care Medicine, Department of Medicine.
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Limper
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D015331:Cohort Studies; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007118:Immunoassay; D007121:Immunocompetence / Q000276:immunology*; D059425:Interferon-gamma Release Tests; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology; D055985:Latent Tuberculosis / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D053262:Receptors, OX40 / Q000276:immunology; D018570:Risk Assessment; D013601:T-Lymphocytes / Q000276:immunology; D055815:Young Adult
chemical_list: D015415:Biomarkers; C508017:IL2RA protein, human; D053645:Interleukin-2 Receptor alpha Subunit; D053262:Receptors, OX40; C505716:TNFRSF4 protein, human
keywords: biomarker; flow cytometry; immunoassay; latent tuberculosis infection; tuberculosis