Hanseníase: pesquisa de marcadores para diagnóstico e prognóstico
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2016-11-11
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Universidade Federal de Goiás
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This thesis concerns two immunologic issues which are relevant for leprosy control activities: laboratory diagnosis of paucibacillary leprosy/PB and evaluation of the prognostic value of Mycobacterium leprae specific serology for leprosy reactions.
Immunodiagnostic laboratory tests for PB leprosy (PB) depend on cellular immunity and these tests and this study evaluated a whole blood assay/WBA prototype using antigen combinations in PB and multibacillary leprosy patients (MB) and controls from two Brazilian endemic regions (Goiânia/GO and Fortaleza/CE). The M. leprae specific cellular immunity was evaluated by WBA using heparinized tubes containing different antigen combinations: 46f+LID-1 and ML0276+LID-1; controls: PBS, PHA, MLCS-M. leprae cell sonicate, PPD. After 24 hours incubation (37°C, 5% CO₂) plasma was collected and ELISA used to detect IFNγ (QuantiFERON/Qiagen, cut-off: 50pg/mL) and CXCL10 (Sigma-Aldrich®, St. Louis, Missouri, USA, cut-off: 500 pg/mL). Newly diagnosed, untreated leprosy patients (MB, n=30, PB, n=38) and controls (27 household contacts/HHC, 61 endemic controls/EC) were tested. The new platform in tube validated previous IFNγ results obtained in culture plates. Production of IFNγ to 46f+LID-1 was detected in 84% PB patients, 55% HHC; for ML0276+LID-1: 71% PB, 55% HHC. For both antigen combinations, the IFNγ response of PB leprosy patients differed from the EC (p<0.0001), however the response in PB leprosy and HHC was similar (p>0.05). Studies in tuberculosis/TB have shown that the CXCL10 response differentiate individuals with active TB from those with latent Mycobacterium tuberculosis infection. In leprosy, CXCL10 levels did not differentiate PB leprosy from HHC. Despite this limitation, our results show that WBA in tube could be a supplementary tool in assessing M. leprae infection rates and evaluating the impact of control measures.
The application of leprosy serology as a predictor for the occurrence of leprosy reactions observed during clinical monitoring post treatment was evaluated by ELISA tests to detect M. leprae-specific antibodies, IgM anti PGL-I, IgG anti LID-1 and IgM and IgG anti ND-O-LID. Serum samples from 452 patients were tested and these patients participated of Clinical Trial for Uniform Multidrug Therapy Regimen for Leprosy Patients in Brazil/U-MDT/CT-B who were clinically monitored for more than six years post treatment for the development of leprosy reactions. Serological tests were performed in samples collected in untreated patients at diagnosis (baseline) and the results were analyzed taking into account the clinical outcome post treatment (reaction and reaction-free). Reactional patients (RR and ENL) had higher seropositivity rates and optical density/OD medians for PGL-I, LID-1 and ND-O-LID compared to reaction-free patients (p<0.0001). In leprosy, both the development of reactions and the serologic response are strongly influenced by the patients’ bacillary index (BI) and a positive correlation was found between both the BI and the proportion of reactional patients and the antibody levels. Negative BI group: 10% reactional patients, intermediary BI (>0<3): 50% reactional patients, high BI (>=3): 66% reactional patients. The serological results stratified according to the BI showed: in BI negative patients higher anti-PGL-I levels in RR patients compared to reaction-free ones (p=0.014); group IB> 0<3: reactional patients (RR) showed higher anti-PGL-I (p=0.014) and anti-LID-1 (p=0.035) antibody levels compared to reaction-free patients; group IB => 3: patients who developed ENL showed higher levels of anti-LID-1 antibodies (p=0.028) when compared with reaction-free ones. The accuracy of a serological test to predict the occurrence of leprosy reactions as determined by ROC curve showed that only anti-PGL-I serology provided limited value to predict RR (area-under-the-curve/AUC=0.702). The anti-PGL-I serology showed low sensitivity for RR prognosis, indicating the need to identify other plasma biomarkers for prediction of RR. In patients who developed ENL during follow-up was observed high positivity in the anti-LID-1 serology at diagnosis indicating the potential application of serology in the identification of patients at higher risk of developing ENL.
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HUNGRIA, EMH. Hanseníase: pesquisa de marcadores para diagnóstico e prognóstico. 2016. 141 f. Tese (Doutorado Medicina Tropical e Saúde Publica) - Universidade Federal de Goiás, Goiânia, 2016.