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Clinical and Vaccine Immunology, May 2007, p. 569-576, Vol. 14, No. 5
1071-412X/07/$08.00+0     doi:10.1128/CVI.00354-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Detection of Anti-Leishmania (Leishmania) chagasi Immunoglobulin G by Flow Cytometry for Cure Assessment following Chemotherapeutic Treatment of American Visceral Leishmaniasis{triangledown}

Elenice Moreira Lemos,1* Izabelle Teixeira Gomes,2 Sílvio Fernando Guimarães Carvalho,3 Roberta Dias Rodrigues Rocha,2 Jauber Fornaciari Pissinate,1 Olindo Assis Martins-Filho,2 and Reynaldo Dietze1

Núcleo de Doenças Infecciosas, Universidade Federal do Espírito Santo, Vitória, Espírito Santo,1 Centro de Pesquisas René Rachou, FIOCRUZ, Belo Horizonte, Minas Gerais,2 Universidade Estadual de Montes Claros, Montes Claros, Minas Gerais, Brazil3

Received 26 September 2006/ Returned for modification 2 January 2007/ Accepted 5 March 2007

The residual serological reactivity observed in patients cured of visceral leishmaniasis (VL) represents the major factor underlying the low efficiency of most anti-Leishmania serological approaches to assess posttherapeutic cure in VL. Herein, we have described a detuned flow cytometry-based methodology to detect anti-live (FC-ALPA-immunoglobulin G [IgG]) and anti-fixed (FC-AFPA-IgG) L. chagasi promastigote IgG, along the titration curve (1:2,000 to 1:128,000), as a tool to assess late (12 months after treatment [12 mAT]) and early (2 and 6 mAT) posttherapeutic cure of pediatric American visceral leishmaniasis. Reactivities were reported as the percentage of positive fluorescent parasite (PPFP), using a PPFP of 50% as a cutoff to segregate positive and negative results. Our data demonstrated that both FC-ALPA-IgG at 1:4,000 and FC-ALPA-IgG at 1:32,000 are useful for late cure assessment in VL, with 100% specificity and outstanding likelihood ratio indices. Cure assessment at 6 mAT also showed promising performance indices, identifying 81% and 71.4% of the treated patients with negative results. However, new interpretation parameters were necessary to monitor cure at 2 mAT. We then introduced the differential PPFP ({Delta}PPFP) of 25% as a new cutoff for early cure assessment at specific serum dilutions to analyze IgG reactivity by FC-ALPA-IgG and FC-AFPA-IgG. Our data demonstrated that at 2 mAT, {Delta}PPFP was >25% in 60% and 57.1% of treated patients, whereas at 6 mAT, a {Delta}PPFP of >25% was observed in 100% and 95.2% of samples assayed by FC-ALPA-IgG and FC-AFPA-IgG, respectively. Together, our findings showed the potential of both FC-ALPA-IgG and FC-AFPA-IgG regarding their applicability to detect differential serological reactivity and further contribution to posttherapeutic cure assessment in VL.

* Corresponding author. Mailing address: Núcleo de Doenças Infecciosas, Universidade Federal do Espírito Santo, Av. Marechal Campos, 1648, Maruípe, Vitória ES 29040-091, Brazil. Phone: 55 (27) 3335-7208. Fax: 55 (27) 3335-7206. E-mail: lemosem{at}ndi.ufes.br

{triangledown} Published ahead of print on 14 March 2007.

Clinical and Vaccine Immunology, May 2007, p. 569-576, Vol. 14, No. 5
1071-412X/07/$08.00+0     doi:10.1128/CVI.00354-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.





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