Anti-Human CD28 (3G5E) Antibody

The 3G5E clone recognizes human CD28, a 44 kDa type I transmembrane glycoprotein expressed primarily on T lymphocytes. CD28 serves as the principal co-stimulatory receptor, binding B7-1 (CD80) and B7-2 (CD86) on antigen-presenting cells to amplify T cell receptor signaling during activation.

This mouse monoclonal antibody is unconjugated and supplied by Antibodies.com as a 100 µl liquid preparation in phosphate buffer containing 150 mM NaCl, 100 mM KCl, and 50 mM sodium phosphate at pH 7.5.

The reagent is validated for flow cytometry (FCM), immunohistochemistry on frozen sections (IHC-Fr), and immunoprecipitation (IP). Investigators also deploy 3G5E in T cell co-stimulation studies, where plate-bound or soluble cross-linking of CD28 substitutes for the natural B7 ligand and rescues IL-2 transcription in TCR-stimulated human peripheral blood mononuclear cells, making the clone a standard tool for dissecting the second-signal axis in vitro.