Available only as minimum quantity of 1 mg.

The monoclonal antibody is directed against the CD28 antigen, which is expressed on a subpopulation of human T cells and activated B cells. It has been shown that CD28 positive cells are cytotoxic T lymphocyte precursors. The monoclonal antibody does not react with B cells, granulocytes and monocytes. In general, two signals are required to activate T lymphocytes into proliferation. In vitro, both signals can be given by the proper combination of monoclonal antibodies, in this respect monoclonal antibodies against CD2, CD3 and CD28 have provided much information on the stimulatory mechanism. It was found that anti-CD2 antibodies are also able to stimulate T cells, although only in the presence of a second signal, which can be given either by more anti-CD2 antibodies directed against other epitopes on the CD2 molecule, and / or e.g. by an anti-CD28 antibody. The binding of anti-CD28 McAbs to T cells was found to enhance stimulation of the cells by anti-CD2 and anti-CD3 mAbs. Therefore, CD28 is regarded as a 'co-stimulatory' molecule. CD28, when stimulated by its ligands B7-1 (CD80) or B7-2 (CD86) provides the co-stimulatory "second signal" required for T cell activation.

Human CD28.
The monoclonal antibody does not react with B-cells, granulocytes and monocytes.