Studies of the numbers and morphology of the intracellular form of Leishmania donovani grown in cell culture.

Abstract

SYNOPSIS. Macrophages were infected in vivo with the intracellular form of Leishmania donovani (LDs), harvested from the previously saline‐stimulated peritoneal cavities of hamsters and explanted into Leighton tubes containing removable coverslips. Serum from either rabbit, chicken, human, calf, hamster or cotton rat blood was used as the 40% component of a Hanks' BSS60 serum40 medium used to maintain these Leighton tube cultures at 37 C. After varying lengths of time coverslips were removed from tubes, stained with Giemsa, and the parasites per infected macrophage, total number of hamster cells and total number of parasites on each coverslip were counted.Maerophages constituted more than 90% of the explanted cells on the coverslips. When cotton rat serum was used as a component of the medium, fibroblastic overgrowth of the coverslips followed. Some similarities and differences in the numbers of macrophages, fibroblasts and parasites were noted with regard to the serum used as part of the medium. Except for cotton rat serum, the serum component of the medium used apparently did not influence, to any great degree, the morphology of either the macrophages or parasites therein. Thus, vacuolarization and granularization of macrophages did not appear to be very distinctly correlated with the time of sampling or the type of serum in the medium used for maintenance nor could any morphologic variations of the LDs be ascribed to these factors.When cotton rat serum, but not any of the other sera, was the serum component of the medium, leptomonads were noted in the overlay fluid of the cultures after 6 days.Under these conditions of cell culture, fibroblasts could not be infected with LDs although macrophages on the same coverslip were heavily parasitized.