Flow cytometric analysis of cellular infiltrate from American tegumentary leishmaniasis lesions

Authors

  • A.M. Da-Cruz,

    1. Laboratório de Imunopatologia, Departamento de Imunologia, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
      *Instituto de Pesquisa Clínica Evandro Chagas (IPEC), FIOCRUZ, Rio de Janeiro, Brazil
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  • A.L. Bertho,

    1. Laboratório de Imunopatologia, Departamento de Imunologia, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
      *Instituto de Pesquisa Clínica Evandro Chagas (IPEC), FIOCRUZ, Rio de Janeiro, Brazil
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  • M.P. Oliveira-Neto,

    1. Laboratório de Imunopatologia, Departamento de Imunologia, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
      *Instituto de Pesquisa Clínica Evandro Chagas (IPEC), FIOCRUZ, Rio de Janeiro, Brazil
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  • S.G. Coutinho

    1. Laboratório de Imunopatologia, Departamento de Imunologia, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
      *Instituto de Pesquisa Clínica Evandro Chagas (IPEC), FIOCRUZ, Rio de Janeiro, Brazil
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  • Conflict of interest: None declared.

Alda Maria Da-Cruz, Av. Brazil 4365, Pav. Leônidas Deane sala 408, Manguinhos, Rio de Janeiro-RJ, Brazil, CEP 21040–900.
E-mail: alda@ioc.fiocruz.br

Summary

Background  CD4+ and CD8+ T lymphocytes play different roles in the outcome of leishmaniasis. However, T-cell distribution in lesions shows significant variability in in situ immunocytochemical studies.

Objectives  In this report flow cytometry was used to determine the predominant T-cell subsets in leishmaniasis lesions, and their relationship with Leishmania-responsive circulating T cells.

Patients and methods  Mononuclear cells from lesions or peripheral blood (PBMC) of 34 cutaneous (CL), four mucosal (ML) and four disseminated leishmaniasis were phenotypically characterized by flow cytometry. Leishmania-responsive T cells were obtained after in vitro stimulation of PBMC with leishmanial antigens.

Results/conclusions  Variable amounts of γδ lymphocytes were present in all lesions, with no association with duration of illness. The highest percentages of interleukin-2R- and interferon-γR-positive cells were observed in ML lesions and could render these T cells more susceptible to the effects of these cytokines. The distribution of intralesional T-lymphocyte subsets was quite variable (CD4+ > CD8+ = 18 cases, CD8+ > CD4+ = 12 cases and CD4+ ≅ CD8+ = 4 cases) without any association with clinical parameters, and could explain the controversy regarding proportions of these T-cell subsets in leishmaniasis lesions. Low percentages of Leishmania-reactive CD8+ T cells were observed in blood while an enrichment of CD8+ cells was shown in the inflammatory infiltrate, suggesting that local immunoregulatory factors could favour the recruitment and/or proliferation of local CD8+ lymphocytes. Increased percentages of CD8+ cells observed in older lesions are consistent with the hypothesis that they can mediate healing, although their involvement in tissue damage cannot be ruled out. It is possible that these mechanisms can influence the clinical outcome or even the response to therapy.

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