New technologies for monitoring human antigen-specific T cells and regulatory T cells by flow-cytometry

•Antigen-specific human Treg and Tcon against any antigen can be identified by functional T cell markers.•MHC-peptide multimers can simultaneously measure T cells against hundreds of defined epitopes.•Magnetic enrichment identifies rare T cell subsets at high resolution.•A comprehensive view on T cell immunity includes naive & memory Tcon and Treg.•New multidimensional single cell analysis tools complement antigen-specific cytometry.

T cells orchestrate and execute immune responses against certain antigens recognized by their antigen receptor. They can acquire a highly divers set of functional properties, which provide the basis for immune protection, but also for immune-pathologies and thus represent highly specific diagnostic and therapeutic targets. New cytometric technologies now allow identification and precise characterization of human conventional and regulatory T cells against basically any antigen and even within naive donors. These provide the basis for thorough analyses of immune protection against infections and to tackle unmet challenges such as T cell responses involved in tolerance and/or directed against undefined or complex antigens, that is, in autoimmunity or allergy. Together with the parallel evolution of single cell multi-parameter approaches this has revolutionized the quantitative and qualitative characterization of human T cells, bearing important diagnostic, prognostic or therapeutic potential.