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American cutaneous leishmaniasis: in situ characterization of the cellular immune response with time
H C Lima1, A W Vasconcelos, J R David
1Nucleo de Medicina Tropical, Universidade Federal do Ceara, Fortalez, Brazil.
Insights
This study investigated immune cells in American cutaneous leishmaniasis lesions. Gamma delta T cells were found to be crucial in the early stages of infection, decreasing over time.
Area of Science:
- Immunology
- Dermatology
- Infectious Diseases
Background:
- American cutaneous leishmaniasis (ACL) is a parasitic disease endemic in Ceara, Brazil, caused by Leishmania braziliensis.
- Understanding the cellular infiltrate in skin lesions is key to elucidating the immune response to ACL.
Purpose of the Study:
- To characterize the cellular infiltrate in skin lesions of patients with ACL using immunohistochemistry.
- To investigate the relationship between lesion age and the cellular phenotype of the infiltrate.
Main Methods:
- Biopsies from ACL lesions (0.5-4 months duration) were analyzed.
- Immunohistochemistry was employed to quantify T cells, T cell subsets (CD4+, CD8+, gamma delta), B cells, and macrophages.
Main Results:
- T cells constituted a significant portion (37.0%) of the infiltrate, with similar proportions of CD4+ and CD8+ T cells.
- Interleukin-2 receptor-positive cells and B cells were infrequent.
- Gamma delta T cells showed a decrease in percentage as lesion age increased.
Conclusions:
- Gamma delta T cells likely play a critical role in the early immune response to Leishmania braziliensis infection.
- The findings suggest gamma delta T cells may be important in the early phase of granulomatous diseases in general.
Abstract:
The cellular nature of the infiltrate in the skin of patients with American cutaneous leishmaniasis was characterized by immunohistochemistry. The study population consisted of patients in Ceara, Brazil, an area where Leishmania braziliensis is endemic. Biopsies were taken from lesions present for 0.5-4 months duration and sections were stained with antibodies to T cells, T cell subsets, B cells, and macrophage markers to quantitate these cell types. The T cells accounted for 37.0 +/- 7.6% (mean +/- SD) of the infiltrate. The average percentages of CD4- and CD8-positive T cells were similar to each other, 20.4 +/- 9.0% and 19.9 +/- 6.7%, respectively. Interleukin-2 receptor-positive cells and B cells were infrequent, 3.7 +/- 3.0% and 2.3 +/- 3.1%, respectively. When the relationship between the age of the lesion at biopsy and the cellular phenotype was examined, it was noted that the percentage of positive cells remained fixed for all cell types except for that of gamma delta cells, which decreased with time. It is likely that gamma delta T cells are important in the early phase of the immune response to L. braziliensis and may, in general, be important in the early immune response of granulomatous diseases.
