Tumor metastases and cell‐mediated immunity in a model system in DBA/2 mice. V. Transfer of protective immunity with H‐2 identical immune T cells from B10.D2 mice

Evidence is presented for the existence of immune T lymphocytes which have protective activity in vivo against the lethal effects of a metastasizing tumor. ESb, the metastasizing tumor cell line of our model system, which is highly malignant in syngeneic DBA/2 mice, can be rejected when transplanted into B10.D2 mice. Since B10.D2 and DBA/2 mice are identical at the H‐2 complex, cells could be transferred from the tumor‐resistant into the susceptible strain to determine whether they could confer protective immunity in a syngeneic environment containing disseminated ESb tumor cells. Protective immunity against ESb could be transferred into DBA/2 with spleen cells but not with ascites fluid from B10.D2 mice preimmunized against the ESb tumor cells. B10.D2 spleen cells taken between 6 and 22 days after tumor transplantation had protective immunity, while cells taken from animals 3 days after tumor transplantation, or from normal animals, had no significant protective effect. The cells in B10.D2 immune spleens with protective activity were sensitive to treatment with anti‐theta serum and complement and did not adhere to nylon‐wool columns. Such nylon‐wool column‐passed cells which were enriched for T lymphocytes had a higher protective activity then the unfractionated cells. DBA/2 mice which received viable ESb tumor cells subcutaneously on day 0 could be protected by intravenous inoculation of B10.D2 immune spleen cells only when these were given after the tumor cells (day +1, +3, +5, +7), not when given before (day −3 or −1). The mechanisms of protective immunity against tumor metastasis and the significance of our findings for completely syngeneic tumor systems will be discussed.