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Adherence of pathogenic and non-pathogenic Entamoeba histolytica strains to neutrophils
1Bernhard Nocht Institute for Tropical Medicine, Clinical Department, Hamburg, Federal Republic of Germany.
Abstract:
The adherence of polymorphonuclear leukocytes (PMNs) to eight pathogenic and nine nonpathogenic strains of Entamoeba histolytica was examined. No difference between pathogenic and nonpathogenic strains was found. The addition of different carbohydrates confirmed the importance of the 170-kDa lectin of E. histolytica in binding to PMNs, corroborated by the finding that treatment of PMNs with galactosidase inhibited adherence. Inhibition of the microfilament system of E. histolytica using cytochalasin B resulted in a loss of adherence to PMNs. Inhibition of the microtubule system using nocodazole did not affect adherence. Preincubation of the trophozoites with serum resulted in enhanced adherence, but the serum factor responsible for this effect could not be identified. Fibronectin, vitronectin, integrins (CD11/CD18 molecules), complement, and mannose-binding protein did not seem to mediate adherence between E. histolytica and PMNs. In summary, these results indicate that defective adherence mechanisms are not a common feature of nonpathogenic E. histolytica strains.
Insights
Nonpathogenic Entamoeba histolytica strains do not exhibit defective adherence mechanisms to polymorphonuclear leukocytes (PMNs). The 170-kDa lectin is crucial for E. histolytica binding to PMNs, independent of pathogenicity.
Area of Science:
- Microbiology
- Immunology
- Cell Biology
Background:
- Entamoeba histolytica is an intestinal protozoan parasite.
- Pathogenic strains of E. histolytica cause amoebiasis, a significant human disease.
- Polymorphonuclear leukocytes (PMNs) are key immune cells involved in combating parasitic infections.
Purpose of the Study:
- To investigate the adherence mechanisms of Entamoeba histolytica to PMNs.
- To determine if adherence differences exist between pathogenic and nonpathogenic strains.
- To identify molecules and cellular processes involved in E. histolytica-PMN interactions.
Main Methods:
- Assessing PMN adherence to pathogenic and nonpathogenic E. histolytica strains.
- Utilizing carbohydrate inhibition assays to probe lectin involvement.
- Employing cytochalasin B and nocodazole to investigate the roles of microfilaments and microtubules.
- Examining the effects of serum preincubation and specific immune molecules on adherence.
Main Results:
- No significant difference in PMN adherence was observed between pathogenic and nonpathogenic E. histolytica strains.
- The 170-kDa lectin of E. histolytica plays a critical role in PMN binding, confirmed by carbohydrate inhibition and galactosidase treatment.
- Inhibition of E. histolytica microfilaments (cytochalasin B) abolished adherence, while microtubule disruption (nocodazole) had no effect.
- Serum enhanced adherence, but the specific factor remains unidentified. Fibronectin, vitronectin, integrins, complement, and mannose-binding protein did not mediate adherence.
Conclusions:
- Defective adherence mechanisms are not characteristic of nonpathogenic E. histolytica strains.
- The 170-kDa lectin and E. histolytica microfilaments are essential for PMN adherence.
- Understanding these interactions may offer insights into host-parasite dynamics in amoebiasis.