Method for producing an examination reagent and kit for analysing a T-cell frequency

A method for producing an examination reagent, the method comprising:

• providing and adding a helper ligand peptide to an unfolded MHC class I receptor protein and β2m in order to produce a folded MHC class I receptor protein, wherein the helper ligand peptide consists of a peptide of 8 to 11 amino acid residues in length and has a lower affinity for a folded MHC class I receptor protein than that of an examination peptide of interest;
• adding a glycyl-leucine (GL) dipeptide as a ligand exchanger/ligand releaser to the folded MHC class I receptor protein, wherein the GL dipeptide has a lower affinity for the folded MHC class I receptor protein than the affinity of the helper ligand peptide for the folded MHC class I receptor protein;
• and
• adding an examination peptide having a higher affinity for the folded MHC class I receptor protein than the affinity of the helper ligand peptide for the folded MHC class I receptor protein, so that the examination peptide is exchanged for the helper ligand peptide, thereby providing the examination reagent, and wherein the MHC class I receptor protein is H-2Kb.