Identification of peptide sequences that potentially trigger HLA-A2.1-restricted cytotoxic T lymphocytes

We used the human processing defective cell line 174CEM.T2 (T2) to identify potential cytotoxic T lymphocyte (CTL) epitopes of human proteins. Exogenously added peptides can increase the number of properly folded HLA-A2.1 molecules on the cell surface of T2 cells, as shown by immunofluorescence measurements using the mouse monoclonal antibody BB7.2 (anti-HLA-A2.1) and fluorescein isothiocyanate-labeled goat anti-mouse F(ab')2 antibody. The peptides were selected on the basis of a computer score derived from the recently described HLA-A2.1 specific motif. Analysis of the influenza matrix protein showed that 15 out of 35 high-scoring peptides up-regulate the expression of HLA-A2.1 molecules on the T2 cell surface. The combination of the computer scoring program and an immunofluorescence-based peptide binding assay allows rapid detection of potential CTL target peptides.