Lacaziosis: immunohistochemical evaluation of elements of the humoral response in cutaneous lesions

• Published in: Revista do Instituto de Medicina Tropical de São Paulo
• Main Authors: Luciane Kanashiro-Galo, Ariane Fernandes Alexandre, Wagner Luiz Tafuri, Tânia Cristina Barboza, Juarez Antonio Simões Quaresma, Arival Cardoso de Brito, Gabriela Yasmin Francisca da Silva do Nascimento, Antonio Marques dos Santos Filho, Mirian Nacagami Sotto, Carla Pagliari
• Format: Article in Journal/Newspaper
• Language: English
• Published: Universidade de São Paulo (USP) 2020
• Subjects: Lacaziosis; Humoral response; Skin; Human lesions; Immunohistochemistry; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1590/s1678-9946202062075; https://doaj.org/article/91e9008328f3415da8c96e3e1241b15a

ABSTRACT Lacaziosis is a cutaneous mycosis caused by the fungus Lacazia loboi, described in different countries of Latin America and prevalent in the Amazon region. The ineffective immune response against the agent seems to be related to a Th2 pattern of cytokines. There are few reports exploring elements of the humoral response in these lesions. Our aim was to investigate some elements focusing on B cells, plasma cells and local expression of IgG and IgM antibodies. Forty skin biopsies of lower limbs were selected. The diagnosis of lacaziosis was based on direct mycological examination and histological analysis. The visualization of fungal cells was improved by using Gridley’s staining. An immunohistochemical protocol was performed to detect the expression of B cells, plasma cells, IgG and IgM. A double staining was performed to explore the presence of yeasts in the cytoplasm of keratinocytes, using an anti-AE1 AE3 antibody over Gridley’s staining. The inflammatory infiltrate consisted of macrophages, multinucleated giant cells, lymphocytes, and fibrosis. Fungal cells were frequent in the stratum corneum and in both, the dermis and, in 50% of the specimens, also in the epidermis. Cells expressing IgG were more abundant when compared to cells expressing IgM. B cells and the presence of IgG might indicate that the humoral response promotes a Th2 immune response resulting in an anti-inflammatory phenotype. Our results lead us to suggest a possible role of B cells and immunoglobulins in the mechanisms of lacaziosis pathogenesis.