The major costimulatory and cytokine receptors involved in cognate donor-antigen specific TFH-B cell interaction are depicted. Biotherapies currently evaluated in clinical trials and their specific targets are represented. This figure was created with BioRender. Abbreviations: CD, cluster of differentiation; ICOS, inducible T cell costimulator; IL, interleukin; MHC, major histocompatibility complex; TCR, T cell receptor.