Apoptosis within mouse eye induced by Toxoplasma gondii

Objective To investigate apoptosis induced by Toxoplasma gondii (T.gondii) in ey es of C57BL/6 (B6) mice.Methods Apoptosis was detected by terminal deoxynucleotidyl transferase-mediated deoxyu ridine triphosphate-biotin nick end labeling (TUNEL) technique and pathological changes within eyes were analyzed at different time points after intraocular in oculation of either 50 or 500 of tachyzoites.Results In eyes that received 50 tachyzoites, a few apoptotic inflammatory cells in the anterior chamber and keratocytes in the cornea were seen at days 1 and 2, but no apoptosis was detected 4 days after inoculation.Significantly greater apoptosi s of inflammatory cells was observed in the anterior chamber and in the vitreous of eyes injected with 500 parasites.Apoptosis of inflammatory cells in the an terior chamber and of keratocytes in the cornea was seen at day 1.The apoptoti c stromal keratocytes strikingly increased at day 4.There were a number of apo ptotic inflammatory cells in the vitreous at day 2, and a few apoptotic retinal cells along the internal limiting membrane and the nerve fiber layer of the reti na 4 days after inoculation.Conclusion These results suggest that apoptosis of inflammatory cells infiltrated eye infec ted with this parasite may be a mechanism of eliminating the organism.