T cell-dependent antitumor immunity mediated by secondary lymphoid tissue chemokine: Augmentation of dendritic cell-based immunotherapy

Secondary lymphoid tissue chemokine (SLC) is a CC chemokine that is selecti ve in its recruitment of naive T cells and dendritic tells (DCs). In the ly mph node, SLC is believed to play an important role in the initiation of an immune response hy colocalizing naive T cells with DC-presenting antigen. Here, we used SLC as a treatment for tumors established from the poorly imm unogenic B16 melanoma. Intratumoral injections of SLC inhibited tumor growt h in a CD8+, T cell-dependent manner. SLC elicited a substantial infiltrati on of DCs and T cells into the tumor, coincident with the antitumor respons e. We next used SLC gene-modified DCs as a treatment of established tumors. Intratumoral injections of SLC-expressing DCs resulted in tumor growth inh ibition that was significantly better than either control DCs or SLC alone. Distal site immunization of tumor-bearing mice with SLC gene-modified DCs pulsed with tumor lysate elicited an antitumor response whereas control DCs did not. We also found that s.c. injection of lysate-pulsed DCs expressing SLC promoted the migration of T cells to the immunization site. This repor t demonstrates that SLC can both induce antitumor responses and enhance the antitumor immunity elicited by DCs.