MHC class II tetramer guided detection of Mycobacterium tuberculosis-specific CD4+ T cells in peripheral blood from patients with pulmonary tuberculosis.

Novel diagnostic tools are needed to diagnose latent infection and to provide biologically meaningful surrogate markers to define cellular immune responses against Mycobacterium tuberculosis (MTB). Interferon gamma-based assays have recently been developed in addition to the more than 100-year-old tuberculin skin test (TST) for the immune diagnosis of MTB in blood. The advent of soluble MHC/peptide tetramer molecules allows to objectively enumerate antigen-specific T cells. We identified novel MHC class II-restricted MTB epitopes and used HLA-DR4 tetrameric complexes to visualize ex vivo CD4(+) T cells directed against the antigens Ag85B and the 19-kDa lipoprotein, shared between MTB and ot…