Correlation between Histopathology, Immune Response, Clinical Presentation, and Evolution in Leishmania braziliensis Infection

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  • Institute of Pathology, Case Western Reserve University, Department of Pathology, University Hospitals of Cleveland, Fundacion Centro Internacional de Entrenamiento e Investigaciones Medicas, CIDEIM, Departamento de Microbiologia, Facultad de Salud Universidad del Valle, Cleveland, Ohio, Colombia

Skin biopsies from 221 parasitologically confirmed cases of tegumentary leishmaniasis caused by Leishmania braziliensis spp. were evaluated with respect to histopathology, the qualitative and quantitative nature of the cellular infiltrate, and the presence of Leishmania amastigotes. These variables were cross correlated with the Leishmania-specific immune response, clinical presentation, and response to treatment. Physical evidence of prior leishmanial lesions was associated with the absence of amastigotes (P ≤ 0.001) and the presence of giant (P = 0.03) and epithelioid cells (P = 0.03) in the biopsy of the active lesion. The presence of amastigotes was inversely related to the duration of the lesion (P ≤ 0.001) and the presence of eosinophils (P ≤ 0.01), whereas the presence of adenopathy (P = 0.01), necrosis (P = 0.001), histiocytes (P = 0.001), and increased serum antibody titer (P = 0.02) were directly associated with the presence of amastigotes. The lymphocyte transformation response was correlated with the presence of granulomas (P = 0.001), but showed no correlation with cutaneous delayed type hypersensitivity. The presence of epithelioid (P = 0.04) and giant cells (P = 0.03) was associated with less drug being required to achieve healing. In contrast, necrosis was associated with a greater amount of drug to achieve healing (P = 0.05). The observed correlations between tissue responses and immune and clinical parameters provide further evidence for the role of antibody and other soluble mediators of the cellular immune response in the evolution of disease. The participation of eosinophils in the tissue response in some individuals suggests that further examination of the function of these cells in human tegumentary leishmaniasis is necessary. Variables associated with the presence or absence of parasites and response to treatment may provide prognostic indices.

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