T Follicular Helper Cell Coculture Assay

T follicular helper (Tfh) cells constitute a distinct subset of CD4+ T cells specialized in providing help to B cells in germinal centers. Phenotypically, Tfh cells are characterized by their high expression of the chemokine receptor CXCR5 that allows their migration into B cell follicles as well as high expression of PD-1, BTLA, the co-stimulatory molecules ICOS and SLAM and the transcription factors BCL6 and cMaf. Tfh cells are the main producers of IL-21 as well as other cytokines like IL-4 and IL-10 critical for B cell survival and differentiation. Tfh cells drive somatic hypermutation and the generation of long-lived memory B cells and plasma cells having an essential role in the development of protective immunity. Developing a coculture system to measure the effects of Tfh-cell mediated B cell help is of great interest to further our understanding of Tfh-B cell interaction and to allow for the manipulation of culture conditions to investigate the potential effect different microenvironment signals or ligand/receptor interactions could have on Tfh cell function.