Ocular toxoplasmosis is a potentially blinding intraocular inflammation. Th
e intent of this study was to investigate the role of Fas-FasL interaction
in a murine model of acquired ocular toxoplasmosis induced by intracameral
inoculation of Toxoplasma gondii. Intraocular inflammation Fas and Fast exp
ression on lymphocytes and on ocular tissues, the occurrence of apoptosis,
and the frequency of CD8(+) and CD4(+) T cells in the infected eyes were an
alyzed in C57BL/6 (B6) mice. Susceptibility to parasite-induced intraocular
inflammation was observed in Fas-deficient (B6-lpr) and FasL-deficient: (B
6-gld) mice. Inoculation of 5,000 T. gondii tachyzoites induced significant
intraocular inflammation associated with increase of Fas and Fast expressi
on in the inoculated eyes of wild-type B6 mice. Flow cytometry demonstrated
a significant increase of Fas and Fast expression on the splenocytes from
naive mice incubated in vitro with the parasite and on the splenocytes harv
ested from the infected mice at day 8 after parasite inoculation. Apoptosis
of inflammatory cells tend cells in ocular tissues was seen, and a greater
frequency of CD8(+) than CD4(+) T cells was observed in the infected eyes,
The intensity of intraocular inflammation was greater in B6-lpr and B6-gld
mice than in wild-type B6 mice (P < 0.05). The results suggest that Fas-Fa
sL interaction associated with apoptosis is involved in the pathogenesis of
acquired ocular toxoplasmosis in mice.