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Naegleria fowleriproduces a fatal disease called primary amebic meningoencephalitis (PAM), which is characterized by an extensive inflammatory reaction in the CNS. It is known that the immune response is orchestrated mainly by neutrophils, which activate several defense mechanisms in the host, including phagocytosis, the release of different enzymes such as myeloperoxidase (MPO), and the production of neutrophil extracellular traps. However, the mechanisms by which amoebas evade the neutrophil response are still unknown. In this study, we analyzed the ability of N. fowlerito respond to the stress exerted by MPO. Interestingly, after the interaction of trophozoites with neutrophils, the amoeba viability was not altered; however, ultrastructural changes were observed. To analyze the influence of MPO against N. fowleriand its participation in free radical production, we evaluated its enzymatic activity, expression, and localization with and without the specific 4‐aminobenzoic acid hydrazide inhibitor. The production of oxidizing molecules is the principal mechanism used by neutrophils to eliminate pathogens. In this context, we demonstrated an increase in the production of NO, superoxide anion, and reactive oxygen species; in addition, the overexpression of several antioxidant enzymes present in the trophozoites was quantified. The findings strongly suggest that N. fowleripossesses antioxidant machinery that is activated in response to an oxidative environment, allowing it to evade the neutrophil‐mediated immune response, which may contribute to the establishment of PAM. Shows Naegleria fowlerihas antioxidant machinery that is activated in response to an oxidative environment, allowing it to evade the neutrophil‐mediated immune response and perhaps contributing to amebic meningoencephalitis.

Currently, there is growing interest in the identification and purification of microbial lectins due to their involvement in the pathogenicity mechanisms of pathogens, such as Entamoeba histolyticaand free-living amoebae. The Gal/GalNAc lectin from E. histolyticaparticipates in adhesion, cytotoxicity and regulation of immune responses. Furthermore, mannose- and galactose-binding protein have been described in Acanthamoeba castellaniiand Balamuthia mandrillaris, respectively and they also contribute to host damage. Finally, in Naegleria fowleri, molecules containing mannose and fucose are implicated in adhesion and cytotoxicity. Considering their relevance in the pathogenesis of the diseases caused by these protozoa, lectins appear to be promising targets in the diagnosis, vaccination and treatment of these infections.