Current methods for assessing T cell responses to influenza.

Traditional methods for the detection of T cell responses to influenza include the lymphoproliferation assay for CD4+ T cells and 51Cr-release assay for the detection of cytotoxic CD8+ T lymphocyte activity. These assays are labour-intensive, require extended periods of cell culture and provide only qualitative data on a bulk population of lymphocytes. Thus, they have been of limited use in dissecting the cellular immune response to influenza infection and vaccination in humans. In recent years, newer methods that detect single cell production of cytokines and binding of tetrameric MHC-peptide complexes by antigen-specific T cells have become available. These assays provide a means of measuring absolute frequencies of functional antigen-specific T cell responses without the need for extended periods of culture. Although still technically demanding, these modern assays represent important new tools for the quantitative analysis of T cell responses to influenza infection and vaccination.