T-cell epitope mapping.

Identification of epitopes defined by T-cell responses aids to (1) monitor antigen-specific cellular immune responses (2) guide rational vaccine design, and (3) understand the nature of protective or harmful T-cell responses in diseases with defined target antigens. The 6-h intracellular cytokine staining (ICS) assay preferentially identifies effector T cells that are readily detectable in the peripheral circulation. In contrast, the whole blood assay (WBA) allows to gauge expansion of antigen-specific T cells over time (7 days), i.e., T cells with lower frequencies (e.g., memory T cells) defined by proliferation and cytokine production. Any cellular immune profile can be measured in the WBA (using the 7 days cell culture supernatants) or directly in responder T cells after antigenic stimulation (in the ICS) with appropriate cytokine-specific detection systems. The choice of the cytokine test panel depends on the nature of the expected immune response. A broad panel of candidate peptides can be tested for T-cell recognition in the WBA due to its simplicity and the low input of (unprocessed, heparinized) blood.