A sensitive proliferation assay to determine the specific T cell response against HLA-A2.1-binding peptides

A proliferation assay to detect a specific T cell response against HLA class I-binding peptides is reported. To establish the specificity and sensitivity of the assay we used a synthetic peptide derived from the CMV glycoprotein B containing the HLA-A2.1 ligand motif. Lymphocyte proliferation was measured following culture of PBMC in the presence or absence of peptide by BrdU uptake. Differing culture conditions were compared (cell number, time in culture, peptide concentration, +/- IL-2). A peptide-specific response was detected in 11 of 23 HLA-A2-positive and CMV IgG-positive donors (47.8%), and in 4 of 36 HLA-A2-positive and CMV IgG-negative donors (11.1%, p = 0.019) tested under optimized conditions. None of 22 HLA-A2-negative individuals tested showed a peptide-specific response and the reproducibility was high. Peptide-specific IFN-gamma-secreting T cells could be demonstrated in responding donors with the ELISPOT assay. This proliferation assay may be suitable for monitoring induction of a specific T cell response against known HLA class I-binding peptides following vaccination with tumor or viral antigens.