Apoptosis of non-parasitized red blood cells in malaria: a putative mechanism involved in the pathogenesis of anaemia.
BACKGROUND
Severe anaemia is a common complication of Plasmodium falciparum malaria in hyperendemic regions. Premature elimination of non-parasitized red blood cells (nRBC) has been considered as one mechanism involved in the genesis of severe malaria anaemia. It has been reported that apoptosis can occur in RBC and, consequently, this cell death process could contribute to anaemia. This study was performed to evaluate the susceptibility of nRBC to apoptosis in a malaria anaemia murine model.


METHODS
Balb/c mice were intraperitonially inoculated with 1 × 106 P. yoelii 17XL parasitized RBC (pRBC) and, then, parasitaemia and anaemia were monitored. Apoptosis in both pRBC and nRBC was assessed during early and late phases of infection by flow cytometry using Syto 16 and annexin V-PE double staining and forward scatter measurement.


RESULTS
As expected, experimental infection of Balb/c mice with Plasmodium yoelii 17XL parasites was characterized by progressive increase of parasitaemia and acute anaemia, leading to death. Flow cytometry analysis showed that a number of pRBC was in the apoptotic process. It was noteworthy that the increase of nRBC apoptosis levels occurred in the late phase of infection, when anaemia degree was notably accentuated, while no significant alteration was observed in the early phase.


CONCLUSIONS
The increased levels of nRBC apoptosis herein firstly reported, in malaria infection could represent a putative mechanism worsening the severity of malarial anaemia.
Laboratory of Malaria Research, Instituto Oswaldo Cruz, Fiocruz, Avenida Brasil, 4365, Manguinhos, 21045-900, Rio de Janeiro, RJ, Brasil.
Paulo R R
PR
Totino
Aline D
AD
Magalhães
Luciene A
LA
Silva
Dalma M
DM
Banic
Cláudio T
CT
Daniel-Ribeiro
Maria de Fátima
Mde F
Ferreira-da-Cruz
D000740:Anemia / Q000473:pathology*; D000818:Animals; D017209:Apoptosis; D004912:Erythrocytes / Q000473:pathology*; D006801:Humans; D008288:Malaria / Q000473:pathology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010967:Plasmodium yoelii / Q000472:pathogenicity*