Cells from lymph nodes (LN) draining progressively growing tumors can differentiate into immune effector cells upon in vitro stimulation with anti-CD3 monoclonal antibodies followed by interleukin-2. The adoptive transfer of these activated LN cells to tumor-bearing mice mediates potent tumor-specific therapeutic effects. In this study, we sought to further characterize the antitumor efficacy and specificity mediated by the anti-CD3/IL-2 activated tumor-draining LN cells against heterologous clones derived from the murine MCA 106 sarcoma. Ten clones of divergent characteristics with regard to morphology, in vivo growth rate, ability to establish pulmonary metastases, MHC class I (H-2) antigen expression, susceptibility to lysis by allogeneic cytotoxic T-lymphocytes, as well as sensitivity to doxorubicin were selected and analyzed. In adoptive immunotherapy experiments, pulmonary metastases derived from each clone were found to be sensitive to the therapeutic effects of activated cells derived from LN draining the parental MCA 106 tumor. The antigenic cross-reactivity was evident from the observation that activated cells from LN draining each of the individual tumor clones were capable of mediating the regression of parental tumor metastases. The specificity of the antitumor reactivities mediated by LN cells draining MCA 106 clones was demonstrated by a lack of in vivo efficacy against metastases derived from the antigenically distinct MCA 205 sarcoma. Additionally, selected clones were tested for their ability to stimulate draining LN against other cloned tumors or used as targets for therapy with activated LN cells draining different clones. In all 29 adoptive immunotherapy experiments, there was complete cross-reactivity between different MCA 106 tumor clones. These findings suggest that the MCA 106 tumor-specific antigen(s) that stimulates draining LN in vivo and recognized by the anti-CD3/IL-2 activated cells is present on most if not all tumor cells. However, in the absence of a demonstrably resistant tumor clone, a very highly polymorphic antigen with many cross-reactive, but distinct epitopes might be operative and attributable to these observations.

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This work was supported in part by USPHS Grant CA-58927 from the National Cancer Institute.

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