Immune privilege is extended, then withdrawn, from allogeneic tumor cell grafts placed in the subretinal space

PURPOSE. To determine whether the subretinal space can extend immune privil ege to allogeneic tumor cell, grafts that do not possess their own inherent immune privilege. METHODS. P815 tumor cells were injected into die anterior chamber (AC), the subretinal (SR) space, or subconjunctivally in eyes of BALB/c (allogeneic) , SCID (immune incompetent), normal DBA/2 syngeneic), or DBA/2 mice presens itized with P815 cells transfected with interleukin-12 and B7.1. Tumor grow th was observed clinically and histologically for up to 50 days. BALB/c rec ipients were tested for suppression of DBA/2-specific delayed hypersensitiv ity and concomitant immunity. The SR space of tumor-containing. eyes was as sessed for its capacity to support ovalbumin (OVA)specific anterior chamber associated immune deviation (ACAID). RESULTS. P815 cells injected into the SK space of presensitized and normal DBA/2 and SCID mice grew progressively, resulting eventually in recipient d eath. Tumor cells injected into the SR space of eyes of BALB/c mice grew pr ogressively until day 14, followed by tumor regression resulting in phthisi s bulbi (14/35) or tumor elimination (19/35) with preserved ocular anatomy by day 35. Despite elimination of tumors from the SR space, BALB/c recipien ts exhibited DBA/2-specific ACAID and concomitant immunity. In addition, OV A injected into the SR space of eyes from which tumor has been eliminated i nduced ACAID CONCLUSIONS. Various parameters of immune privilege, originally described f or the AC, are characteristic of immune privilege within the SR space. Howe ver, because P815 cells placed in the AC prove lethal for BALB/c recipients , but P815 cells placed in the SR space resolve without jeopardizing the ho st's life, immune: privilege in the SR space can be distinguished from immu ne privilege in the AC, and this may have implications for grafts of retina l tissue placed within the SR space.