In situ cellular immune response in non-ulcerated skin lesions due to Leishmania (L.) infantum chagasi infection

 

Carmen Sandoval1, Gabriela Araujo1, Wilfredo Sosa1,2, Sara Avalos3, Fernando Silveira4,5, Carlos Corbett1, Concepción Zúniga6, Marcia Laurenti1

 

1 Laboratory of Infectious Diseases Pathology, Department of Pathology, Medical School (FMUSP), University of São Paulo (USP), São Paulo, SP, Brazil.

2 Microbiology Research Institute, National Autonomous University of Honduras, Tegucigalpa, Honduras.

3 Master Program in Infectious and Zoonotic diseases, School of Microbiology, National Autonomous University of Honduras, Tegucigalpa, Honduras.

4 Department of Parasitology, Evandro Chagas Institute, Secretariat of Health Surveillance, Ministry of Health, Belém, PA, Brazil.

5 Institute of Tropical Medicine, Federal University of Pará, Belém, PA, Brazil.

6 Department of Health Surveillance, School Hospital, Tegucigalpa, Honduras.

 

Abstract

Background: Skin lesions of patients affected by non-ulcerated cutaneous leishmaniasis (NUCL) caused by L. (L.) infantum chagasi are characterized by lymphohistiocytic inflammatory infiltrate associated with epithelioid granuloma and scarce parasitism. However, the in situ cellular immune response of these patients is unclear. Therefore, the aim of the present study was to characterize the cellular immune response in the skin lesions of patients affected by NUCL.

 

Methods: Twenty biopsies were processed by immunohistochemistry using primary antibodies to T lymphocytes (CD4, CD8), NK cells, B lymphocytes, macrophages, nitric oxide synthase and interferon-gamma.

 

Results: Immunohistochemistry revealed higher expression of all cellular types and molecules (IFN-γ, iNOS) in the dermis of diseased skin compared to the skin of healthy individuals (p < 0.05). Morphometric analysis performed in the skin lesions sections showed the predominance of CD8+ T lymphocytes in the mononuclear infiltrate, followed by macrophages, mostly iNOS+ , a response that could be mediated by IFN-γ.

 

Conclusion: Our study improves knowledge of the cellular immune response in nonulcerated or atypical cutaneous leishmaniasis caused by L. (L.) infantum chagasi in Central America and pointed to the pivotal participation of CD8+ T lymphocytes in the host defense mechanisms against the parasite in patients with NUCL.

 

Keywords: Non-ulcerated cutaneous leishmaniasis Atypical cutaneous leishmaniasis Leishmania infantum chagasi Cellular immune response Immunohistochemistry Honduras

 

Correspondence: mdlauren@usp.br

 

Received: 13 October 2020; Accepted: 25 January 2021; Published online: 26 February 2021