During amoebic infection, neutrophils are the first cells of the immune system to interact with trophozoites of Entamoeba histolytica, initiating amoebicidal activity. Different lectins and carbohydrates can participate in the mechanism of adhesion between E. histolytica and the target cell through the recognizing of carbohydrates by the lectins present in the cells and the parasite. The formation and release of NETs (neutrophil extracellular traps) are damage mechanisms in response to amoebae. NETs consist of DNA and antimicrobial enzymes such as myeloperoxidase (MPO). It is not known whether carbohydrates are able to block the formation and release of NETs or their compounds, such as MPO enzyme, in the interactions between carbohydrates-preincubated amoebae and neutrophils. E. histolytica 260 kDa and 220-kDa lectins are glycoproteins that can stimulate the formation of neutrophil NETs. Our results showed that the formation of neutrophil NETs was prevented mainly by the carbohydrates N-acetyl-α-D-galactosamine (GalNAc) or N-acetyl-α-D-glucosamine (GlcNAc) in the interactions of neutrophils with carbohydrate preincubated E. histolytica but did not prevent a significant increase in the activity of the MPO enzyme or damage to trophozoites, suggesting that other mechanisms of neutrophil damage, such as MPO enzyme, are involved in amoebic damage. Our results revealed that incubation of amoebae with GalNAc increased neutrophil MPO enzyme activity, possibly in part through the inhibition of the amoebic 260-kDa lectin.
Levaro-Loquio et al. (Thu,) studied this question.