Analysis of cytotoxic T cell responses to intracameral allogeneic tumors.

Injection of P815 mastocytoma tumor cells into the anterior chamber (AC) of BALB/c mice results in progressively growing intraocular tumors, whereas injection of the same dose of tumor cells subcutaneously results in rapid rejection of the tumor. Previous results indicated that AC P815 inoculation results in an unorthodox immune response characterized by suppressed delayed hypersensitivity, elevated antibody levels and priming for cytotoxic T lymphocyte (CTL) activity. Since mice inoculated in the AC with P815 cells display progressively growing intraocular tumors in spite of the fact they are primed for CTL activity, we examined whether the differential tumor growth patterns between AC and SC inoculation are the result of an aberrant and weak cytotoxic response in the former. We analyzed the lytic activity, target specificity and frequency of cytotoxic precursors and effector cells in the spleen following AC and SC inoculation of P815 cells. Our results indicate that both AC and SC routes of P815 inoculation generate splenic CTL effector cells with equivalent lytic activity for P815 tumor target cells. These effectors are highly specific for P815 cells and do not lyse third-party EL-4 targets. Analysis of the frequency of cytotoxic T cell precursors (pTc) in the spleen and lymph nodes of animals that received AC and SC injections revealed that both routes generated comparable pTc frequencies. Thus, tumor cells placed in the anterior chamber are capable of generating a full complement of cytotoxic precursors and effectors, that are equivalent to those that are generated following SC injection. Therefore, the progressive growth of the tumor in the eye cannot be attributed to a defect in the tumor-specific CTL response.