The 37.51 monoclonal antibody specifically reacts with mouse CD28 molecule, a 45 kDa homodimer. It is expressed on most thymocytes, at low density on most of the CD4+ and CD8+ peripheral T lymphocytes, and on the natural killer cells. It is additionally found on activated splenocytes, mast cells, and thymocytes. CD 28 is a costimulator of T lymphocytes and a ligand for CD80 (B7-1), and CD86 (B7-2). The CD28 signaling stimulates the expression of IL-2 and IL-2 receptor and the cytotoxicity of CD3-activated T lymphocytes.
The 37.51 antibody stimulates the proliferation of T lymphocytes and natural killer cells and their respective cytokine production.