Co-stimulation by CD28

CD28 signaling plays a critical role in shaping immune responses by ensuring effective T-cell activation and enhancing T-cell survival and proliferation. When CD28 engages its ligands, B7-1 (CD80) and B7-2 (CD86), on antigen-presenting cells, it provides an essential secondary signal that complements T-cell receptor (TCR) activation. This costimulatory signal leads to the production of interleukin-2 (IL-2), which supports the clonal expansion of T cells, promoting both their proliferation and survival by initiating anti-apoptotic pathways.

Summary from Reactome (R-HSA-389356), read 2026-09-23.