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Iván Best1, Angela Privat1, Patricia Reyes1, Francesca Falconi1, María Cruz2, Jean-Loup Lemesre3, Jorge Arévalo1, RAPSODI consortium
1Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru; 2Hospital Regional ESSALUD, Cusco, Peru; 3IRD, France.
Methods. Fifty-seven subjects (32 men/25 women) from the highlands of Cusco, Peru (Fig. 2): 28 who have visited an endemic area without any disease sign (SEA), 7 with CL, 12 with ML and 10 healthy subjects from of a non-endemic area (SNEA) were enrolled. The asymptomatic infection was defined in the SEA group by a specific-T cell proliferation using peripheral blood mononuclear cells (PBMC) stimulated for 5 days with a local total soluble leishmanial antigen of L. braziliensis. T cell proliferation was evaluated by [3H] thymidine incorporation. Cytokine Th1/Th2/Th17 patterns (IL-17A, IFN-, TNF-, IL-10, IL-6, IL-2) were quantified in the supernatants by a flow cytometry multiplex assay.
Background. Clinical manifestastions of American Tegumentary Leishmaniasis (ATL) include cutaneous (CL) and mucous forms (ML); however, it is conceivable that there are individuals who might be infected but not present any clinical manifestations, as reported other types of Leishmaniasis. These individuals, here called asymptomatic, may show a natural resistance to develop ATL diseases. The aim of this study was to characterize the cellular immune response of asymptomatic individuals who were exposed to Leishmania by short periods of time during seasonal work in endemic areas (Fig. 1). Their immune response will be compared with CL and ML subjects that acquired the disease under similar conditions.
Conclusions. Our results showed two discrete groups among subjects apparently healthy that might be exposed to Leishmania parasites in endemic areas. We propose that T-cell proliferation and IFN- discriminated individuals who were Leishmania infected but asymptomatic from individuals that we assumed were non infected during seasonal work in the Amazon jungle.
Correspondence: [email protected]://www.upch.edu.pe/tropicales/index.asp
Immunological screening of asymptomatic Leishmania infection in individuals exposed to an endemic area of
American Tegumentary Leishmaniasis (ATL)
Results. T-cell proliferation stimulation index (SI) cut-offabove 2.47 was used to define an asymptomatic infection (Fig. 4): 15 out of 28 SEA (53.57%) presented significantly higher SI compared to 13 remaining SEA (4.5 vs. 1.32, P<0.001). CL and ML patients presented SI of 77.6 and 22.2, respectively. An increased specific IFN- production was observed in SEA with SI above the cut-off compared to SNEA (18.6 vs. 4.0 pg/ml, P<0.05) (Fig. 5). IFN- levels in CL and ML patients were 3259 and 4674 pg/ml, respectively. For the remaining cytokines, there were no significant differences between SEA with SI above the cut-off and SNEA. In CL and ML patients, high levels of TNF- and IL-10 were observed. No immunological differences were found between SEA with SI below the cut off and SNEA.
NPD2010/48
Figure 1. Seasonal work in the peruvian forest. Figure 2 Endemic areas of Leishmaniasis and Migration Areas In Cusco.
MigrationEndemicAreas
Relevance. The search of asymptomatic individuals (Fig. 3) who were exposed to an endemic area of ATL will allow to identify markers of a natural resistance and select a suitable population for vaccine trials.
Figure 4. T-cell proliferation stimulation index (SI) in individuals exposed to an endemic area of American Tegumentary Leishmaniasis. Red line limits the cut-off.
Acknowledgment: This work was supported by the 7th Framework Programme (FP7) of the European Comission. Virbac SA, Institut pour la Recherche et le Développement (IRD), Instituto de Salud Carlos III (ISCIII), Indian Council of Medical Research (IOP), Universidad Peruana Cayetano Heredia (UPCH), Institut Pasteur de Tunis (IPT), Alma Consulting Group (ALMA) and Instimed SARL (INSTIMED) are members of the RAPSODI consortium.
Figure 5. IFN- levels in asymptomatic Leishmania infection. Only P-values indicating significant differences are shown, * P < 0.05.
A B
Figure 3. Clinical examination of A. Symptomatic with uvula infiltration and eritema plus edema in palate. B. Asymptomatic candidate. These individuals did not show any observable sign.
0
4
8
12
16
20
24
28
Control SNEA with SI > 2.47 SNEA with SI < 2.47
IFN
-gam
ma
(pg/
ml)
(n = 10) (n = 13) (n = 15)
*
0.00
2.47
4.94
7.41
9.88
12.35
14.82
17.29
19.76
22.23
24.70
27.17
RAP
-33
RAP
-36
RAP
-39
RAP
-32
RAP
-136
RAP
-137
RAP
-138
RAP
-139
RAP
-140
RAP
-141
RAP
-145
RAP
-147
RAP
-148
RAP
-149
RAP
-150
RAP
-151
RAP
-152
RAP
-154
RAP
-159
RAP
-162
RAP
-163
RAP
-165
RAP
-168
RAP
-169
RAP
-171
RAP
-173
RAP
-174
RAP
-176
Stim
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dex
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