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Buenos Aires, Argentina

De Leon P.P.,Laboratorio Of Parasitologia | Biondi C.,Laboratorio Of Inmunohematologia | Valverde J.,Laboratorio Of Inmunohematologia
Acta Bioquimica Clinica Latinoamericana | Year: 2010

Sialic acids (SA) contained in glycoproteins and glycolipids participate in various biological functions; besides, its presence on the erythrocyte surface has both hemodynamical and hemorheological importance. SA are thought to intervene in the parasite-host interaction. The aim of this work was to study the effect of Ascaris lumbricoides on the erythrocyte superficial charge by using Polybrene Method. Work was carried out on 51 adult parasite extracts ([AE]) and 4 (larvae) larvae concentrates ([ALLC]: 2000 / 1000 / 500 / 250 larvae/ mL). The method was applied to non-treated (Control) and treated red cells with [AE] / all 4 [ALLC] simultaneously. Larvaé treatment was conducted over 18 experiences. Erythrocytes treated with 37. 25% of the [AE] had lower aggregation than the Control. The statistical analysis showed that this effect was not related to the protein concentration of [AE]. The aggregate decrease in the treatment with [ALLC] was dependent on larvae concentration and it was related to larvae concentrations ≥ 500 larvae/ mL. It was observed that the [AE]/ [ALLC] fixation to the erythrocyte was not strong. The results have shown that A. lumbricoides sequestrates SA erythrocyte. This capture could affect the pathology and/or participate in the escape of the host's immune response. Source


De Leon P.P.,Laboratorio Of Parasitologia | Foresto P.,Laboratorio Of Inmunohematologia | Valverde J.,Laboratorio Of Inmunohematologia
Acta Bioquimica Clinica Latinoamericana | Year: 2010

Molecular mimicry has been associated with chronicity of parasitic infections. This mechanism can be due to absorption of the host's molecules or to synthesis of similar molecules. P1 has been detected in various parasite species. Previous experiences have shown P1 epitopes in Ascaris lumbricoides's adult parasites. The aim of this study was to analyse absoption of these epitopes by nematode larvae in order to determine the mechanism by which the parasite can express these antigens on their cuticle. Larvae were hatched from the faeces with helminth eggs. Larvae were cultivated in RPMI medium with P1 red cells. The Quantitative Inhibition Agglutination Test was performed using 4 anti- P1 monoclonal antibodies. P1 fresh red cells in bromelin enzymatic medium was used as revealing system. Simil P1 excretory-secretory products were investigated using larvae cultivated in RPMI medium without P1 erythrocytes by the same technique. The larvae which were cultivated with red cells inhibited the agglutination between all anti-P1 monoclonal antibodies and P1 erythrocytes. Simil P1 excretory-secretory products were not identified. It was demonstrated that A. lumbricoides larvae absorb P1 epitopes from the culture medium. It can be concluded that the parasite can absorb this antigen during its life cycle in order to use it in molecular mimicry. Source


De Leon P.P.,Laboratorio Of Parasitologia | Foresto P.,Laboratorio Of Inmunohematologia | Valverde J.,Laboratorio Of Inmunohematologia
Acta Bioquimica Clinica Latinoamericana | Year: 2010

Hyaluronic acid (HA) participates in the immune response because it is a constituent of natural mechanical barriers, an inflammation stimulator and a ligand for receptors involved in immunity. Previous experiences have shown that adult specimens and larval concentrates of A. lumbricoides have hyaluronan binding capacity. The aim of this work was to study the kinetics of hyaluronic acid capture by this parasite. Work was carried out with an extract of adult specimen and a larval concentrate. The modified test of serum soluble CD44 Detection by Aggregation Inhibition was used. Kinetics hyaluronic acid capture by the nematode was assessed by varying the contact time between HA and parasite, from an initial time to 90 minutes, with 10-minute intervals. C expAdhEHA and IexpCPHA were calculated for all the times and they were analysed by Wilcoxon and Friedman Tests The results showed that at initial time of contact, the adult parasite and the larvae had captured a small amount of HA. The major capture was made at 10 minutes and it was maintained for 50 minutes without significant differences. From that time there was a slight increase in capture and it remained so until the end of the experiment without considerable variations. This experience demonstrates that at 10 minutes of in vitro contact, A. lumbricoides captures most of the HA, which suggests that in vivo, the parasite would be able to capture HA quickly for the purpose of modulating the immune response. Source


De Leon P.P.,Area de Parasitologia | Menendez M.,Area de Parasitologia | Biondi C.,Laboratorio Of Inmunohematologia | Valverde J.,Laboratorio Of Inmunohematologia
Acta Bioquimica Clinica Latinoamericana | Year: 2012

The aim of this work was to study the A. lumbricoides' effect on the anionic charge of erythrocytes and desyalated erythrocytes. Work was carried out on 30 extracts ([AE]) and 2 larval concentrates ([ALLC] 1: 500-600; ([ALLC] 2: 200-300 larvae/ mL) of the parasite and Group O erythrocytes in saline (RC) and enzymatic medium (RCb). The red cell sediment was incubated with an equal volume of parasite and the Control (RCc) with, 7PBMsaline solution, at 37°C. Polybrene and Alcian Blue Methods were applied and Aggregation Titulation from Polybrene was implemented. The coefficients for each method were defined,which were analyzed statistically. The results showed that a longer treatment and also at higher larval concentration,increased the capture of sialic acid (AS),while decreasing the RC and RCb aggregation. The effect was greater on the incubation of the parasite with RCb in relation to RC. The enzymatic treatment reduced similarly the percentage charge in the globules incubated with both [ALLC] (16% -17% of initial) and the variation of RC and RCb charge due to both was about 10%,indicating that the charge loss caused by [ALLC]1 was significant with regard to [ALLC]2. We concluded that A. lumbricoides can capture erythroctyte SA. This phenomenon would contribute to explain the anaemia and thrombi produced in ascariosis,noting that in patients with AS deficit pathologies,these complications would be more relevant. © 2012 Federacion Bioquimica de la Provincia de Buenos Aires. Source


De Leon P.P.,Laboratorio Of Parasitologia | Di Vita S.,Laboratorio Of Parasitologia | Biondi C.,Laboratorio Of Inmunohematologia | Valverde J.,Laboratorio Of Inmunohematologia
Acta Bioquimica Clinica Latinoamericana | Year: 2012

Red cell polyagglutination may be due to the unmasking of the cryptic T antigen by the action of microbial neuraminidases, which remove terminal sialic acid residues in the erythrocyte membrane. Previous experiences showed that Ascaris lumbricoides capture erythrocyte sialic acid and that globular suspensions in enzymatic medium, incubated with this parasite, completely lost the ability to aggregate. The aim of this work was to study the erythrocyte T antigen exposure by A. lumbricoides action on the anionic charge of sialic acid deficient red cells. Studies were done on 48 adult specimen parasite extracts ([AE]) and an L1/ L2 larvae concentrate ([ALLC]: 1300-1500 larvae/mL). Group O red cells in bromelain enzymatic medium (RCB) and Control erythrocytes in saline medium (RCC) were used. The RCB sediment was incubated with an equal volume of [AE]/ [ALLC] and the RC C sediment with physiological solution during 120 minutes at 37 °C. Plate and Tube Agglutination Tests were performed, contrasting RC B and RCC with adult and cord human sera. The results showed that 33.33% of the RCB incubated with [AE] and 66.67% of the RCB incubated with [LCAL] agglutinated with serum from adult, but not cord serum. RCB were not agglutinated with any of the sera. It is the first time that erythrocyte T antigen exposure by a parasite action is communicated. T activation could produce autoagglutination and haemolysis in the adult and would represent a transfusion risk factor in the child population. Source

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