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Properties of red cell ghost preparations susceptible to invasion by malaria parasites
Abstract:
Experimental procedures are described that lead to the formation of sealed red cell ghosts capable of efficient invasion by malaria parasites. Both human and monkey cells have been studied with respect to invasion by Plasmodium falciparum and P. knowlesi respectively. Resealed ghosts containing about half the normal concentration of haemoglobin are prepared by osmotic lysis and resealing at a haematocrit of 70%. When examined in the scanning electron microscope, populations of these ghosts contain few echinocytes, but have an abundance of stomatocytic forms. When undiluted haemolysate is substituted for the aqueous saline diluent, in which the cells are suspended for lysis and resealing, discocytes result, with a morphology very similar to that of the original cells. Invasion is somewhat, but not dramatically higher for this material. An investigation of the effect of intracellular potassium concentration revealed that this had no major effect on invasion. A small increase in invasion resulted from addition of 50 or 100 mg/ml of albumin to the medium in which the cells were resealed, but intra-erythrocytic protein content per se is evidently not a major factor in determining the efficiency of invasion. Augmentation of the cytoplasmic ATP concentration during lysis and resealing increased the level of parasitaemia significantly, and the parasites in these ghosts developed normally and gave rise to viable merozoites. It was found that albumin at certain concentrations passed freely into the lysed cells and reached equilibrium with that in the external medium. By contrast, the high molecular weight solute Blue Dextran 2000 was completely excluded from the lysed cells.
Insights
Researchers developed resealed red blood cell ghosts for malaria parasite invasion studies. Augmenting cytoplasmic ATP significantly increased parasitaemia, enabling normal parasite development and merozoite production.
Area of Science:
- Cell biology
- Parasitology
- Biochemistry
Background:
- Efficient invasion of red blood cells by malaria parasites is crucial for understanding disease transmission.
- Previous methods for creating red blood cell ghosts had limitations in maintaining cellular integrity and supporting parasite invasion.
- Investigating factors influencing red blood cell invasion by Plasmodium species is essential for developing new therapeutic strategies.
Purpose of the Study:
- To establish a method for generating sealed red blood cell ghosts suitable for efficient malaria parasite invasion.
- To investigate the effects of various cellular and medium components on parasite invasion efficiency.
- To optimize conditions for red blood cell ghost preparation to support normal parasite development.
Main Methods:
- Preparation of red blood cell ghosts via osmotic lysis and resealing at high hematocrit.
- Morphological analysis of ghosts using scanning electron microscopy.
- Assessment of malaria parasite (Plasmodium falciparum and Plasmodium knowlesi) invasion efficiency under different conditions, including varying intracellular ATP and albumin concentrations.
Main Results:
- Resealed ghosts with high hemoglobin concentration were successfully prepared, exhibiting stomatocytic and discocytic forms.
- Augmentation of cytoplasmic ATP concentration during resealing significantly increased parasitaemia and supported normal parasite development.
- Albumin in the resealing medium enhanced invasion, while high molecular weight solutes like Blue Dextran 2000 were excluded.
Conclusions:
- The developed method produces functional red blood cell ghosts capable of supporting efficient malaria parasite invasion.
- Cytoplasmic ATP levels are a critical factor in determining the efficiency of red blood cell invasion by malaria parasites.
- This technique provides a valuable tool for studying malaria parasite-host cell interactions and for screening antimalarial compounds.