title: IFN-γ production to leishmania antigen supplements the leishmania skin test in identifying exposure to L. braziliensis infection.
abstract: BACKGROUND
  Cutaneous leishmaniasis due to L. braziliensis (CL) is characterized by a positive delayed type hypersensitivity test (DTH) leishmania skin test (LST) and high IFN-γ production to soluble leishmania antigen (SLA). The LST is used for diagnosis of CL and for identification of individuals exposed to leishmania infection but without disease. The main aim of the present study was to identify markers of exposure to L. braziliensis infection.  METHODOLGY/PRINCIPAL FINDINGS: This cohort study enrolled 308 household contacts (HC) of 76 CL index cases. HC had no active or past history of leishmaniasis. For the present cross-sectional study cytokines and chemokines were determined in supernatants of whole blood culture stimulated with SLA. Of the 308 HC, 36 (11.7%) had a positive LST but in these IFN-γ was only detected in 22 (61.1%). Moreover of the 40 HC with evidence of IFN-γ production only 22 (55%) had a positive LST. A total of 54 (17.5%) of 308 HC had specific immune response to SLA. Only a moderate agreement (Kappa = 0.52; 95% CI: 0.36-0.66) was found between LST and IFN-γ production. Moreover while enhancement of CXCL10 in cultures stimulated with SLA was observed in HC with DTH+ and IFN-γ+ and in patients with IFN-γ(+) and DTH(-), no enhancement of this chemokine was observed in supernatants of cells of HC with DTH(+) and IFN-γ(-).
  
  
  CONCLUSIONS
  This study shows that in addition of LST, the evaluation of antigen specific IFN-γ production should be performed to determine evidence of exposure to leishmania infection. Moreover it suggests that in some HC production of IFN-γ and CXCL10 are performed by cells not involved with DTH reaction.
authors.affiliation: Serviço de Imunologia, Complexo Hospitalar Universitário Prof. Edgard Santos, Universidade Federal da Bahia, Salvador, Brazil.
authors.forename: Daniel
authors.initials: D
authors.lastname: Schnorr
authors.forename: Aline C
authors.initials: AC
authors.lastname: Muniz
authors.forename: Sara
authors.initials: S
authors.lastname: Passos
authors.forename: Luiz H
authors.initials: LH
authors.lastname: Guimaraes
authors.forename: Ednaldo L
authors.initials: EL
authors.lastname: Lago
authors.forename: Olívia
authors.initials: O
authors.lastname: Bacellar
authors.forename: Marshall J
authors.initials: MJ
authors.lastname: Glesby
authors.forename: Edgar M
authors.initials: EM
authors.lastname: Carvalho
mesh_terms: D000293:Adolescent; D000328:Adult; D000953:Antigens, Protozoan / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D059425:Interferon-gamma Release Tests / Q000379:methods*; D007892:Leishmania braziliensis / Q000276:immunology*; D016773:Leishmaniasis, Cutaneous / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D010274:Parasitology / Q000379:methods*; D012882:Skin Tests / Q000379:methods*; D055815:Young Adult
chemical_list: D000953:Antigens, Protozoan