FLUOROCHROMES: PACIFIC BLUE, FITC, PE, PERCP, PERCP-CY5.5, APC, AL. FLUOR 700.

CD28 is a 44 kD disulfide-linked homodimeric type I glycoprotein. It is a member of the immunoglobulin superfamily also known as T44 or Tp44. CD28 is expressed on most T lineage cells, NK cell subset, and plasma cells. CD28 binds both CD80 and CD86 using a highly conserved motif MYPPY in the CDR3-like loop. CD28 is considered as a major co-stimulatory molecule, inducing T lymphocyte activation and IL-2 synthesis and preventing cell death. In vitro studies indicate that ligation of CD28 on T cells by CD80 and CD86 on antigen presenting cells provides a costimulatory signal required for T cell activation and proliferation. The CD28.2 antibody co-stimulates T cell proliferation and cytokine production in the presence of suboptimal amounts of anti-CD3 antibody.