The aim of the current study was to evaluate the therapeutic use of tumor-specific T-cells obtained from s.c. Ag (antigen)-loaded sponge implants. Naive C57BL/6 mice were implanted with small, polyurethane sponges containing irradiated FBL-3 tumor cells. On day 10, cells that had accumulated in the sponges were harvested and tested for specific cytolytic and proliferative function in vitro. The results demonstrated that CD8+ and CD4+ T-cells immune to FBL-3 could both be primed in and obtained from the Ag-loaded sponge implants. Limiting dilution analysis demonstrated that the frequency of FBL-3-specific cytotoxic T-lymphocytes elicited from Ag-loaded sponges was four times greater than the frequency from draining lymph nodes and at least 50 times greater than from spleen and peripheral blood. Tumor-specific T-cells could similarly be obtained from Ag-loaded sponges implanted into previously primed mice and into mice bearing disseminated FBL-3. In both circumstances, elicited T-cells exhibited much higher cytolytic activity than T-cells from sponges implanted in naive mice, indicating an in situ accumulation and expansion of primed T-cells in response to the antigen stimulation. Tumor-specific T-cells obtained from Ag-loaded sponge implants could be grown long-term in vitro by periodic restimulation with irradiated FBL-3 and low concentrations of interleukin 2. Adoptive transfer of the resultant expanded T-cell lines into mice with disseminated FBL-3 revealed that cultured sponge-infiltrating T-cells could mediate effective antitumor therapy. Thus, in vivo immunization with Ag-loaded sponges provides a potentially useful technique for procuring primed, Ag-specific T-cells for tumor therapy.