FLT3 ligand administration inhibits tumor growth in murine melanoma and lymphoma.

Successful treatment of melanoma and lymphoma may result from the induction of specific antitumor immunity. Dendritic cells (DCs) are powerful antigen-presenting cells and show a remarkable capacity to stimulate antigen-specific T-cell responses. Administration of FLT3 ligand (FL) results in a reversible accumulation of functionally active DCs in both lymphoid and nonlymphoid tissues. Therefore, we evaluated the possible antitumor effect of FL in murine melanoma (B16 and CL8-1) and lymphoma (EL-4) models. In all experiments, tumor growth was significantly inhibited by FL administration. Analysis by immunohistochemistry revealed an increase in the DC accumulation within B16 and EL-4 tumors after treatment with FL. No change was observed for CL8-1 melanoma. These data suggest a potential role for FL in the immunotherapy of malignant skin tumors and possible DC involvement in this effect.