Purification of malarial parasites (Plasmodium falciparum, Plasmodium berghei, Plasmodium vivax, and Plasmodium yoelii)

The use of a 12.5% (w/v) Nycodenz density barrier to enrich for either gametocytes or ookinetes from cultures of Plasmodium falciparum was first described by Carter et al [1] who reported that viability of the parasites purified in this manner is greater than those purified in Percoll.

 Later, a 10% (w/v) Nycodenz cushion was used to harvest macrogametes and zygotes from Plasmodium berghei while if 12% (w/v) Nycodenz was used the material contained, in addition, ookinetes [2].

 In a threelayer gradient of 6%, 11% and 16% (w/v) Nycodenz, macrogametes and zygotes from Plasmodium falciparum banded at the 6%/11% interface [3,4]. This three-layer gradient is a widely used approach for separating various forms of the organism [5-7]. 

Mons et al [8], who used either a 16% or 16.5% (w/v) Nycodenz cushion to concentrate the parasites from Plasmodium vivax cultures, reported that although the interfacial material contained mainly parasitized erythrocytes, some leukocytes, large erythrocytes and erythrocyte ghosts were observed. 

The enrichment on the 16% Nycodenz was noticeably higher (400-4200x) than on the 15% Nycodenz (10-200x). The 16.5% Nycodenz barrier was also found to provide an approx. five-fold enrichment of reticulocytes. A barrier of 12-16% (w/v) is widely used to purify a variety of parasitized erythrocytes