Circulating T Follicular Helper Subsets in Human Blood

CXCR5+ memory CD4+ T cells in human blood represent a circulating compartment of T follicular helper (Tfh) cells (termed circulating Tfh: cTfh cells). cTfh cells are composed of subsets that differ in phenotype and functions, and include resting and activated cell populations. Analysis of cTfh cell subsets have proven to be valuable to assess the ongoing global Tfh cell responses in vivo in distinct medical conditions including autoimmune diseases, infectious diseases, and after vaccination. Herein we will describe a detailed protocol to analyze cTfh subsets in human blood samples and to assess their helper capacity in culture with B cells.