Dynamics of the Interaction between Entamoeba histolytica and Components of the Immune Response

Abstract

The possible implications of cell membrane dynamics in the host--parasite relationship has been studied. Entamoeba histolytica rapidly redistributed and internalized antibodies and Con A bound to its surface. The process was dependent on temperature, cell metabolism and changes of pH in the environment. Phagocytizing amoebae displayed a higher rate of membrane perturbations, which were similarly affected by temperature, cell metabolism and pH variations. Cytochalasin B partially inhibited the redistribution whereas colchicine did not. Colchicine in combination with Cytochalasin B augmented the inhibitory effect of Cytochalasin B alone. The expression of antigens at the surface of the amoeba showed cyclic fluctuations during cell growth.

Complement resistance of pathogenic Entamoeba histolytica mediated by trypsin-sensitive surface component(s)

“…In E. histolytica, capping had been shown for membrane-bound VOL. 61, 1993 antibodies (2,3) and had also been reported for C3 products (13). Cell fixation with glutaraldehyde inhibits capping and additional clearance mechanisms of the cell membrane such as shedding and internalization.…”

“…Besides high-Mr bands presumably representing nonreleased C3 products, the presence of a 105-kDa band corresponding to the a' chain is notable since it indicates that hemolytically active C3b was bound to the ameba surface. 3 min, they were resuspended and incubated in 1 M hydroxylamine (pH 10.5) containing 5% SDS at 95°C for 10 min to cleave the ester bond between 125I-C3 products and the parasite membrane (14). After centrifugation at 12,000 x g for 5 min, the supematants were submitted to 5 to 15% gradient SDS-polyacrylamide gel electrophoresis (PAGE) under reducing conditions and then autoradiography.…”

Exploring the Possible Role of Lysine Acetylation onEntamoeba histolyticaVirulence: A Focus on the Dynamics of the Actin Cytoskeleton

“…Capping formation is another actin cytoskeleton dependent process [10, 11]. With this purpose we examined, by confocal microscopy, the mobilization of Con A towards the posterior cap in trophozoites treated or not with Aspirin or with DMSO, after interaction with Con A for 15 min.…”

“…Incubation of live trophozoites of E. histolytica with FITC-concanavalin A (Con A) was carried out as described earlier [10, 11]. After 15 min of interaction with the lectin, cells were fixed with 4% paraformaldehyde for 30 min, and actin was revealed with rhodamine-phalloidin (1 : 25) and nucleus with DAPI (1 : 300).…”

“…The invasive process of Entamoeba histolytica , the etiologic agent of human amebiasis, is driven by motility, and cytoskeleton dynamics is indispensable for parasite invasion [9]. Moreover, it has been well documented that the actin cytoskeleton participates in capping formation in E. histolytica, which has been proposed as an effective way of evading the host immune response by rapid mobilization of surface receptors into the cap and its further release [10, 11]. …”