Ascaris lumbricoides: alteration of the erythrocyte superficial charge using the Partition Method in aqueous two-phase system

Abstract

SUMMARYSialic acid is responsible for the negative charge of the erythrocyte. The decrease of sialic acid has hemodynamical and hemorheological importance. The aim was to study the effect of A. lumbricoides on the erythrocyte superficial charge using the Partition Method in aqueous two-phase system in order to indirectly evaluate the alteration of sialic acid in the red cells.We worked with five parasite extracts (AE) and larvae concentrate (LC). Erythrocyte superficial charge was studied by working with non-treated (Controls) and treated erythrocytes. The treatment consisted of incubating the erythrocytes with AE or LC for 30 minutes at 4 ºC, 20 ºC and 37 ºC. The red cells were separated in a sensitive charge two-phase system (Dx/ PEG). The partition coefficient (P) of treated and untreated erythrocytes were calculated. The results showed a P decrease at the three temperatures for red cells treated with four of the AE. The remaining extract did change P values at any of the temperatures studied. The erythrocytes treated with LC showed a decrease in the P value at 37 ºC and 4 ºC but no change was observed at 25 ºC. Statistical analysis concluded that P values were significantly lower in treated erythrocytes than in their corresponding untreated ones (p < 0.05). The Partition Method showed that this parasite alters the erythrocyte superficial charge which may indicate that it can catch sialic acid. KEYWORDS: Ascaris lumbricoides; Erythrocyte charge; Partition method.Sialic acid is responsible for the negative charge of the erythrocyte membrane and contributes to the structural properties of the glycophorines. A decrease in the contents of sialic acid in the membrane promotes erythrocyte aggregation, rouleaux formation, decrease in the blood flow and increase in blood viscosity, which results in a greater interaction between erythrocytes and vascular endothelium 8 . Cellular mechanisms of many infectious processes are not known with accuracy and they may involve host and parasite surface glycoconjugates. Trypanosoma cruzi takes sialic acid from the host glycoconjugates and transfers it to molecules on its surface. Taking hold of sialic acid makes T. cruzi resistant to the attack of complement proteins and antibodies of cytolitic capacity 5 . In trypanosomiasis caused by T. congolense, T. brucei and T. evansi the adhesion phenomenon of the parasites to erythrocytes and endothelial cells is mediated by structures which contain sialic acid residues 2,4,9 . The existence of invasion ways through acid sialic receptors in Plasmodium falciparum has been communicated 7 . The occurrence of sialic acid in different parasite infections with endocellular replication has been reported but there are no reports of its role in Ascaris lumbricoides. The aim was to study the effect of A. lumbricoides on the erythrocyte superficial charge using the Partition Method (PM) in aqueous two-phase system in order to indirectly evaluate the alteration of sialic acid in the red cells.Five parasite extracts (AE) and a larvae concentrated (LC)...