Described are a T cell immune response cDNA 7 (TIRC7) encoding a T-cell transmembrane protein, peptides and polypeptides derived therefrom and antibodies recognizing such (poly)peptides. Peptides, polypeptides and antibodies capable of inhibiting T-cell stimulation through the T-cell membrane protein (TIRC7) are provided. Vectors comprising polynucelotides encoding such polypeptides and peptides, host cells transformed therewith, and their use in the production of such, peptides or polypeptides are also described.