Interaction between macrophages of various origin and Toxoplasma gondii under conditions in vitro.

The study of proliferation of a virulent strain of Toxoplasma in cultures of macrophages of various origin revealed a certain sequence in the development of the pathogen: penetration and phagocytosis of the parasite, the stage of disintegration of one part of population and active proliferation of the other, resulting in the destruction of host cells. It was found that the penetration and phacocytosis were more active if macrophages from resistant animals (rats) were used, in comparison with those isolated from susceptible animals (white mice, guinea pigs). The activity of proliferation of a virulent strain of Toxoplasma also differs with the host cells: the toxoplasma multiply more rapidly in macrophages from susceptible animals than in those from resistant animals. The following changes of macrophages due to proliferation of the parasite were observed: change of form of the cell accompanied with the loss of cytoplasmatic processes, vacuolation of the cytoplasm, displacement of the nucleus towards the periphery followed by its pycnosis and rupture of the cell.