Background The mechanisms that mediate immune protection in individuals with subclinical (SC) or asymptomatic infection with L. braziliensis are largely unknown. Neutrophils (PMNs) have been implicated in progressive symptomatic cutaneous leishmaniasis (CL), but their potential participation in maintenance of subclinical infection is unexplored. The aim of this study was to compare the phenotypic and functional profiles of PMNs in individuals with SC infection versus patients with symptomatic CL due to L. braziliensis. Methods Subjects were recruited in the endemic region of Corte de Pedra, Bahia, Brazil. Surface markers to define activation status were characterized by flow cytometry. Functional responses of PMNs including phagocytic capacity, production of oxidative species, and oxidative killing of intracellular parasites were studied in vitro. Results PMNs from individuals with SC infection displayed a more activated phenotype and greater ability to control the infection than PMNs from patients with CL. In contrast, PMNs from patients with CL exhibited higher expression of HLA-DR and higher production of oxidative species than PMNs from subjects with SC infection. Conclusion PMNs from individuals with SC infection can control the infection more efficiently than PMNs from patients with CL, despite the lower production of oxidants. Our observations suggest that L. braziliensis may evade microbicidal mechanisms of PMNs from patients with CL, contributing to parasite dissemination and the establishment of disease.

中文翻译：

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无症状与有症状巴西利什曼原虫感染期间中性粒细胞的对比表型


背景 巴西乳杆菌亚临床 (SC) 或无症状感染个体介导免疫保护的机制在很大程度上尚不清楚。中性粒细胞（PMN）与进行性症状性皮肤利什曼病（CL）有关，但其在亚临床感染维持中的潜在作用尚未被探索。本研究的目的是比较 SC 感染个体与巴西乳杆菌引起的有症状 CL 患者的 PMN 表型和功能特征。方法 在巴西巴伊亚州科尔特德佩德拉流行地区招募受试者。通过流式细胞术表征定义激活状态的表面标记。体外研究了中性粒细胞的功能反应，包括吞噬能力、氧化物质的产生和细胞内寄生虫的氧化杀伤。结果 SC 感染个体的 PMN 表现出比 CL 患者的 PMN 更活跃的表型和更强的控制感染的能力。相反，与 SC 感染受试者的 PMN 相比，CL 患者的 PMN 表现出更高的 HLA-DR 表达和更高的氧化物质产生。结论 尽管产生的氧化剂较低，但来自 SC 感染者的 PMN 比来自 CL 患者的 PMN 更有效地控制感染。我们的观察结果表明，巴西乳杆菌可能逃避 CL 患者中 PMN 的杀菌机制，从而促进寄生虫传播和疾病的形成。