Intracellular Multiplication of Toxoplasma gondii in Adult Mammalian Macrophages Cultivated in vitro

Abstract

To evaluate cellular factors determining resistance to infection with Toxoplasma gondii. infected macrophages from normal and immunized adult laboratory animals were cultivated in vitro. Multiplication of the parasites and the fate of the infected cells served as indicators for the outcome of the interaction between the 2 systems. High species susceptibility brings about rapid intracellular multiplication of the parasites and extensive destruction of Toxoplasma containing cells in vitro. The parasites multiply more slowly within macrophages from naturally resistant animals, such as rats, and destruction of the host cells is less apparent. Immunization with small doses of living Toxoplasma results in the formation of antibodies which when added to the culture system reduce multiplication of the parasites. The cells of immunized animals were also found to inhibit intracellular propagation. The inhibitory power of serum and cells from immunized animals, combined, completely prevented intracellular multiplication.