Flt3 ligand enhances the immunogenicity of a gag-based HIV-1 vaccine

Liposomes and Flt3 ligand (Flt3L), a ligand for the fms-like tyrosine kinas e receptor Flt3/FLK2, can augment the immune response to an HIV peptide vac cine. The HGP-30 peptide used in these studies is a synthetic peptide that corresponds to a highly conserved region of HIV-1 p17 gag (amino acids 86-1 15). Mice were immunized with HGP-30 or HGP-30 conjugated to keyhole limpet hemocyanin (KLH) and delayed-type hypersensitivity (DTH) responses, antibo dy (IgG) amount and antigen-specific proliferative responses by spleen cell s were used to monitor the immune response. Daily injections of Flt3L prior to HGP-30 administration enhanced significantly an antigen-specific lympho cyte proliferation response when compared with Flt3L, HGP-30 alone or HGP-3 0 containing liposomes. Intravenous administration of HGP-30 was superior t o intramuscular (i.m.) immunization for the induction of DTH responses. The HGP-30/KLH containing liposomes enhanced both DTH and antibody responses, while liposomes containing HGP-30 peptide elicited only T cell responses. I n these studies, either Flt3L or liposomes increased DTH responses compared with the i.m. injection of the HGP-30 vaccine alone. (C) 2000 Internationa l Society for Immunopharmacology. Published by Elsevier Science Ltd. All ri ghts reserved.