Generation Of T Follicular Helper Cells In Vitro: Requirement For B-Cell Receptor Cross-Linking And Cognate B- And T-Cell Interaction

The minimum requirements for invitro modelling of natural CD4(+) T-cell differentiation into T follicular helper (Tfh) cells are still under investigation. We co-cultured wild-type and T-cell receptor (TCR) transgenic CD4(+) T cells from naive mice with dendritic cells and B-cell receptor (BCR) transgenic B cells in the presence of HIV-derived virus-like particles containing matched B-cell and T-cell epitopes. This co-culturing induced co-expression of Tfh-master regulator transcription factor BCL-6 and CXCR5 in up to 10% of the wild-type and up to 40% of the TCR-transgenic CD4(+) T cells. Phenotypic markers, production of interleukin-21 and isotype switching of the B cells to IgG1 further indicated a helper function of the induced Tfh cells invitro. Dendritic cells supported the generation of functional Tfh cells, but were unable to induce them without cognate B cells. Hence, our study presents a robust experimental system for efficient generation of functionally active Tfh cells invitro and confirms the importance of cognate B- and T-cell cross-talk for the Tfh differentiation process.