Simultaneous transduction of B7-1 and IL-2 genes into human melanoma cellsto be used as vaccine: enhancement of stimulatory activity for autologous and allogeneic lymphocytes

In order to construct an immunogenic cellular vaccine, we transduced three HLA-A*0201 human melanoma lines, selected for expression of classes I and I I HLA, adhesion molecules and the T cell-defined melanoma antigens Melan/MA RT-1, gp100 and tyrosinase, with both interleukin-2 (IL-2) and B7-1 genes b y the use of a polycistronic retroviral vector. The lines were selected to share only the HLA-A*0201 allele to avoid generation of strong alloreactivi ty in case of their multiple in vivo use in HLA-A*0201 + patients. Phenotyp ic and functional analysis of B7-1-IL2 transduced melanoma lines in compari son with B7-1 transduced and/or parental untransduced counterparts were the n carried out. Tumor cells expressing either B7-1 or both genes did not cha nge their original antigenic profile. From a functional point of view, expr ession of both genes in melanoma lines: (1) improved the response of anti-m elanoma cytotoxic T lymphocytes (CTL) over singly transduced or untransduce d melanoma cells when subthreshold levels of MHC-peptide complexes were exp ressed by melanoma cells; (2) conferred a distinct advantage in the ability to stimulate cytotoxicity and interferon-gamma release by autologous and/o r HLA-A*0201-compatible allogeneic lymphocytes; (3) allowed the generation of a high number of specific CTL by in vitro stimulation of lymphocytes of HLA-A*0201-melanoma patients. Thus, B7-IL2 gene-transduced melanoma lines a ppear to display a high immunogenicity and could be used as vaccine in mela noma patients.