FLT3 LIGAND INDUCES TUMOR-REGRESSION AND ANTITUMOR IMMUNE-RESPONSES IN-VIVO

Daily treatment of mice with recombinant human Flt3 ligand (huFlt3L) r esults in a dramatic numerical increase in the number of dendritic cel ls (DCs) in vivo. Since DCs are pivotal in the induction of immune res ponses, we tested whether Flt3L treatment of mice challenged with a sy ngeneic methylcholanthrene (MCA)-induced fibrosarcoma would augment th e generation of effective antitumor immune responses in vivo. Flt3L tr eatment not only induced complete tumor regression in a significant pr oportion of mice, but also decreased tumor growth rate in the remainin g mice. A preliminary characterization of the cellular mechanisms invo lved suggests that Flt3L may be important in the treatment of cancer i n situ through the generation of specific antitumor immune responses.