The human immune system constantly provides a balance between pathogen clearance as
well as tolerance for autoantigens and the commensal microbiota. This is achieved by
immune responses, which are highly specialized and diversified in terms of their phenotype,
function, regulation and location. Despite the complexity that is inherent to human immunity,
our current knowledge is primarily shaped by very reductionist insights gained from
peripheral blood T cells. Since only 2% of human T cells recirculate in the blood, the vast …