Cultivation of the erythrocytic stages of Plasmodium berghei in Leydig cell tumor cultures.

Twelve different established cell-lines were used in attempts to cultivate the erythrocytic stages of Plasmodium berghei, P. vinckei vinckei, P. coatneyi or P. knowlesi. Intracellular parasites were seen in only mouse Leydig cell testicular tumor (LCT) cultures inoculated with red cells infected with P. berghei. Intracellular parasites were present at 15 to 96 h after inoculation, being most numerous at 36 h. Most intracellular stages were rings, trophozoites, schizonts and merozoites; gametocytes were few in number and present only at 36 and 48 h. Intracellular parasites were normal in general morphology and staining characteristics at 15 to 48 h, but were abnormal after 72 h. Infected host cells exhibited progressive nuclear and cytoplasmic degenerative changes, which ultimately resulted in death of the cell. Uninfected cells appeared normal. The ability of parasites in LCT cultures to produce infections upon injection into mice was similar to that obtained with control cultures without LCT cells.