Panels of normal BALB/c mice received injections of P815 cells (2×
10
5/site) into the SR space, the AC, or
subconjunctivally. The growth of these tumors was examined by direct
inspection, by slit-lamp, by indirect ophthalmoscopy, and, eventually,
by histology of enucleated tumor-bearing eyes. As described
previously,
12 tumors grew progressively within the AC and
the SR space (
Fig. 1A ,
Table 1 ) through day 14. By day 14 post-implantation, tumor
cells had broken through the sclera and penetrated into the orbit
(Fig. 1B) . In contrast, P815 cells injected subconjunctivally formed
transiently growing masses that promptly receded and were no longer
evident at 14 days
(Table 1) . Beyond 14 days, the patterns of tumor
growth in the AC and SR space began to differ. Whereas the AC tumors
simply continued to grow progressively beyond day 21 post-implantation,
SR space tumors began to recede when examined at this time point
(Table 1) . Eyes with P815 cells in the SR space then progressed toward one of
two outcomes:
phthisis bulbi was observed by day 30 in 19 of
35 eyes; complete tumor elimination with preserved ocular morphology
was observed in 14 of 35 eyes
(Table 1) . Two eyes showed slowly
progressing tumor growth that was still evident when the experiment was
terminated on day 60 post-implantation. These findings indicate that
immune privilege was extended equally well to allogeneic tumor cells
injected into the AC and SR space for the first 2 weeks after
implantation. Thereafter, privilege was apparently lost in the SR
space, and as a consequence the tumors (with or without the eye) were
destroyed.