A pharmaceutical composition contains an antibody or a fragment thereof specific for COL6A3 for the treatment of a cancer. A method of treating a cancer includes administering to a subject in need thereof the pharmaceutical composition. A kit includes a container that contains the pharmaceutical composition. A method of producing an antibody or a fragment thereof against a peptide or a MHC/peptide complex. A method for detecting a diseased tissue includes administering to a subject in need thereof an antibody or a fragment thereof conjugated to a radioisotope and detecting a signal from the radioisotope in the subject. A method for treating a diseased tissue includes administering to a subject in need thereof an antibody or a fragment thereof conjugated to a toxin.