TUMOR SPONGE IMPLANTATION - AN INVIVO METHOD FOR STUDYING SYNGENEIC, PRIMARY ANTI-TUMOR LYMPHOCYTE-RESPONSES

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  • 1 January 1982
    • journal article
    • research article
    • Vol. 42  (2) , 397-404
Abstract
Sponge matrices surgically implanted in the s.c. space of the back of normal BALB/c mice were injected with a regressor dose of Moloney sarcoma virus-induced BALB/c tumor cells [MSV-124]. The kinetics of the generation of cytotoxic cells within the sponge was studied over a 22-day period in a short-term 51Cr release assay. Cytotoxic activity peaked on day 16 and then declined to negligible levels by day 22. No cytotoxicity was detectable when nontransformed BALB/c blast cells, Moloney leukemia virus-induced tumor (LSTRA) cells or unrelated chemically induced tumor (EL4) cells were used as targets. When the cellular composition of implanted tumor sponges was examined on day 16, it was 30-40% myeloperoxidase-positive cells, 15-25% surface Ig-positive cells and 40-50 .theta.-positive cells. Treatment with anti-Thy 1.2 plus complement eliminated the cytotoxic response on day 16. The ratio of T-cells to tumor cells within the sponge was determined by immunofluorescence. Kinetic studies showed that the number of .theta.-positive cells increased well before cytolytic activity was detected, possibly reflecting increasing numbers of amplifier T-cells or cytotoxic cell precursors. A later decline in .theta.-positive cells correlated directly with decreased cytotoxicity. Furthermore, onset of cytotoxic activity also correlated with a decline in the percentage of Moloney murine sarcoma virus tumor cells within the sponge. Sponge cells isolated on day 16 (peak cytotoxicity), mixed with lethal dosages of Moloney murine sarcoma virus tumor cells, successfully neutralized the lethal challenge demonstrating the in vivo antitumor efficacy of these effector cells. Sponges were also implanted in mice which had been immunized with a single injection of Moloney murine sarcoma virus cells. Inoculation of the sponge with tumor cells resulted in a 2nd set response in which cytotoxic cells appeared much earlier than in unsensitized animals. Cells from spleen, lymph node or peritoneal cavity of normal or presensitized animals with tumor sponge implants were not cytotoxic, suggesting a highly localized response.