• Parasites, Hosts and Diseases
• /
• v.33 no.3
• /
• pp.173-178
• /
• 1995

A quantitative assay was performed on the effects of gamma-irradiation (30- 300 Gy) on intracellular proliferation of Toxoplosmn gonnii RH tachyzoites in human leukemic HL-60 cells and murine peritoneal macrophages by means of 3H-uracil uptake assay. Infected non-irradiation group (NI) and uninfected group (incubating only host cells) were prepared. The 3H-uracil uptake by tachyzoites of NI group 12-24 hrs after infection was 2,190-4,787 counts per minute for macrophages and 2,967-8,254 for HL-60 cells, whereas the irradiated tachyzoites revealed only 381-703 (100 Gy) and 218-408 (300 Gy) for macrophages, and 1,911-2,618 (30 Gy), 1,253-1,384 (70 Gyl, 1,013-1,090 (100 Gyl, and 483-588 (300 Gy) for HL-60 cells. The proliferation inhibition rate was similar in macrophages and HL-60 cells, for example, 89-94% and 80-94% respectively by 300 Gy, 12-24 hrs after infection. It is concluded that RH tachyzoites of T gondii are severely affected by gamma-irradiation in their capability of Intracellular proliferation.

• Parasites, Hosts and Diseases
• /
• v.35 no.2
• /
• pp.79-86
• /
• 1997

Toxoplasmn gonnii, an intracellular protozoan infecting many kinds of eukaryotic cells, has been used to experimentally infect macrophages, epithelial cells, fibroblasts, and various cancer cells, but rarely T and B Iymphocytes or granulocytes. The present study was performed to determine the susceptibility of murine (BALB/c or CBA) splenic T and B llrnphocytes, and granulocytes to infection trio T. gondii RH tachyzoites. The ultrastructure of the infected host cells was observed by TEM, and the degree of intracellular parasite proliferation was quantified using 3H-uracil uptake assay. At 24 hrs post-culture, the host cell cytoplasm was found to contain 1 or 2, or a maximum of 7-8 tachyzoites. Infected T Iymphocytes demonstrated a peripherally displaced nucleus, a parasitophorous vacuole enveloping the parasite, and an increased number of mitochondria. In B Iymphocytes infected with tachyzoites, RER was not well developed compared to uninfected B Iymphocytes. Uninfected granulocytes contained many electron dense granules, but T. gondii-infected granulocytes demonstrated a decreased number of granules. Based on the 3H-uracil uptake assay. the susceptibility of T and B Iymphocytes, and granulocytes, to infection with T. gonnii tachyzoites was fairly high irrespective of cell type and strain of mouse. This strongly suggests deterioration in the functioning of infected host immune cells.

• Parasites, Hosts and Diseases
• /
• v.31 no.3
• /
• pp.215-222
• /
• 1993

In order to establish a useful cell culture system for T gondii we compared the degree of proliferation of T gondii tachyzoites among 8 different cell lines: 2 kinds of normal animal cells (MDCK-canine kidney cells; Vero-monkey kidney cells) and 6 kinds of human tumor cells (A 549, PC 14-lung cancer cells; SNU 1, SNU 16. Mlm 45-stomach cancer cells; HL-60-promyelocytic leukemia cells), through morphological observation and 3H-uracil uptake assay. The degree of susceptibility to infection with T gondii tachyzoites was highest in A 549 and PC 14 cells, medium in Vero, HL-60, MDCK and SNU 1, and lowest in SNU 16 and MBm 45 cells. The kinetics of T gondii multiplication during the post-Infection 60 hours were higllly dependent upon the dose of tachyzoites administered and the duration among the 8 tested fur the growth and multiplication of T gondii in vitro.

• Parasites, Hosts and Diseases
• /
• v.32 no.1
• /
• pp.19-26
• /
• 1994

An in uipo culturing to examine the cyst stage of ToxopLQsma gondii (ME49 strain) was Investigated using murine peritoneal macrophages, and we also examined the effect of CAMP or DHFR Inhibitors on the growth of bradyzoltes. For experiments ICR mice were Injected 1.p. with 1,500 brain cysts. At 1, 3, 5 and 7 days, peritoneal exudates were Isolated and then adherent peritoneal macrophages were cultured for 1,3,5 and 10 days. Growth pattern of bradyzoltes was measured by (3H)-uracil uptake assay and morphological pattern of pseudocysts formed in macrophages was observed Uth Glemsa stain. Mostly bradyzoites were observed In the macrophages extracted at 3 and S days post Infection. After 3 days in vitro, a number of pseudocysts were formed in the macrophages and the size of pseudocysts was increased during further 5 and 10 days in vitro culture. CAMP stimulated the growth of bradyzoltes when in uiuo 3 and 5 days and then in vitro 5 and 10 days conditions were applied. In case of.DHFR Inhibitors, pynmethamlne produced a linearly decremental effect with a cont.-dependent mode but methotrexate was not effective against Intracellular bradyzoltes or pseudocysts In this system. It was suggested that cyst-forming strain of T gondii (ME49 strain) could be maintained and cultivated in uitro by use of murine peritoneal macrophages. In uivo 3 and 5 days and then in uiko 5 and 10 days conditions appeared to be suitable for culturing of bradyzoltes. CAMP and pyrimethamine had an effect of stimulation and inhibition on the growth of bradyzolte, respectively.