Die Chemokine RANTES, MIP-1α und MIP-1ß spielen eine entscheidende Rolle bei T-Zell vermittelter Tumorregression

Abstract

Introduction: Understanding the mechanisms involved in T-cell-mediated tumor regression is critical to develop and improve immunotherapy trials. Recently we could show that mice could be cured of established pulmonary metastases of the murine melanoma B16BL6 (D5) by adoptively transferred tumor-specific effector T-cells (T_E) from wild-type (wt), perform k/o (PKO), FasL mutant (gld) and IFN-γ k/o (GKO) mice. These observations question the importance of direct cytotoxicity or type-1 cytokines (IFN-γ) in T-cell-mediated tumor regression. Therefore, the aim of our present study was to identify factors, involved in tumor regression after adoptive transfer of tumor-specific T_E. Methods: For the induction of tumor-specific T_E wt and GKO mice were vaccinated s.c. with 10⁶ D5-G6. D5-G6 is a stable GM-CSF-transduced clone of the murine melanoma D5. T-cells generated from the tumor vaccine draining lymph nodes (TVDLN) were stimulated in vitro with anti-CD3 and expanded in low doses of IL-2. T_E were adoptively transferred into wt and GKO mice with established pulmonary D5 metastases. 24- and 48 hours after adoptive transfer the lungs of the treated animals were examined immunohistochemically. The tumor-specific chemokine expression of T-cells and of D5 tumor cells were determined by RT-PCR and ELIS A. Furthermore, the secretion of chemotactic factors by T_E was determined by investigating the migration of macrophages (DJ2pm) in transwell plates after stimulation of T_E with D5 or control tumor. Results: The lungs of treated wt and GKO animals show an infiltration of macrophages most pronounced around the metastases 24 hours after adoptive transfer of wt and GKO T-cells. T_E from wt and GKO mice secrete RANTES tumor specifically (p < 0,05). T_E express tumorspecifically the chemokines Rantes, MlP-lα and MIP-lβ. After stimulation of T_E with D5 the migration of macrophages was significantly induced. Summary: Adoptive transfer of T_E induces the infiltration of macrophages into the lungs of animals with established pulmonary metastases. T_E secrete RANTES, MlP-lα and MIP-lβ tumor-specifically, which are chemoattractive for macrophages. Thus, we believe that chemokines play an important and underestimated role in T-cell mediated tumor regression and may function as adapters inbetween the innate and adaptive anti-tumor immune response.