Concentration and purification by magnetic separation of the erythrocytic stages of all human Plasmodium species

The magnetic removal of non-parasitized red blood cells (in vivo and in vitro) using magnetic columns (MACS) was evaluated. This easy-to-use technique enriched schizonts and gametocytes from Plasmodium falciparum in vitro cultures with a very high degree of purity. In addition, all haemozoin-containing stages (schizonts and/or gametocytes) from the peripheral blood of infected patients could be concentrated using this method. This method is particularly useful for the concentration of non-falciparum species, which do not grow in culture and are otherwise difficult to obtain in large amounts.Falciparum malaria is one of the most common diseases in tropical countries. There are about 300 million new cases, and more than two million deaths due to this illness every year [1]. Different methods have been described to isolate and/or purify living parasites from in vitro cultures or from murine Plasmodium [2,3]. However, non-falciparum species of human Plasmodium (namely Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae) are not easy to purify or concentrate from the blood of infected patients. Difficulties in producing large amounts of parasite material from the blood stages of Plasmodium sp. have restricted progress in research on non-falciparum malaria, but also studies on gametocyte biology. Moreover, in endemic regions, the use of an easy single-step method for the purification and/or concentration of the gametocytes could be useful for biological and epidemiological studies [4]. The property of all human Plasmodium species to degrade haemoglobin (an Fe(II) diamagnetic complex) into haemozoin (an Fe(III) paramagnetic complex) was used, making possible the magnetic purification of parasitized red blood cells containing haemozoin. The present study demonstrates the high degree of purity that can be obtained for the synchronization of in vitro cultures of Plasmodium falciparum, either on asexual or sexual erythrocytic stages, and the usefulness of magnetic sepa