Patent ID: 7109026

Claim:
A tumor cell transfected with a DNA coding for at least one MHC class II ligand selected from the group consisting of LAG-3, and a derivative thereof that maintains the ability to bind the MHC Class II molecules which bind LAG-3, wherein said LAG-3 derivative is a mutant or a soluble fragment of LAG-3 selected from the group consisting of a soluble fragment of LAG-3 consisting of at least one of the four immunoglobulin extracellular domains, a fragment of LAG-3 consisting of the extracellular domains D1 and D2, a fragment of LAG-3 consisting of the four immunoglobulin extracellular domains, and a mutant form of a soluble LAG-3 comprising the extracellular domains D1 and D2, said mutant being defined by one or more amino acid substitutions selected from the group consisting of: Arg at residue position 73 substituted with Glu; Arg at residue position 75 substituted with Ala; Arg at residue position 75 substituted with Glu; and Arg at residue position 76 substituted with Glu.