Quantitation of antigen-specific CD8+ T-cell responses.

Enumeration of antigen-specific CD8+ T-cells has traditionally been largely dependent on the use of techniques that require a period of expansion in vitro. However the recent emergence of methods that can be used directly ex vivo to quantify antigen-specific CD8+ T cells has prompted a re-evaluation of the magnitude of viral-specific cellular immune responses. The purpose of this review is to describe the commonly used methods currently available to quantify and characterise antigen-specific T-cells and then to focus in more detail on the use of tetrameric complexes of HLA/peptide to study the cellular immune response.