CD40 ligand (CD40L)/CD40 signaling plays a crucial role in T cell–dependent B cell differentiation and maturation. The mechanism of CD40 signaling in B cells has been well established, and its importance in immune responses is well documented. However, the modulation of CD40 ligand signaling by transmembrane proteins has not been fully explored. This research activity aims to investigate the role of transmembrane proteins in modulating CD40 ligand signaling and its impact on immune responses.