Abstract Text: Signals through CD28 provide important co-stimulation for optimal T cell activation. Anti-CD28 antibodies have been widely used as T cell costimulation reagents in T cell studies and/or T cell expansion. We recently developed a panel of new anti-human CD28 monoclonal antibodies. Preliminary characterization demonstrated that these antibodies can provide effective costimulation for T cell activation/proliferation with suboptimal TCR stimulation. In addition, this effort also identified antibodies that can activate human T cells to proliferate without TCR stimulation, indicating super-agonistic function of these antibodies. In vitro culture experiments showed that these super-agonistic antibodies promoted T cell survival and proliferation. Importantly, FoxP3+ Treg cells proliferated to greater extend under super-agonistic anti-CD28 stimulation than under routine anti-CD3/anti-CD28 activation. This study is to further characterize the functions of these new anti-CD28 antibodies and their potential application in Treg cell expansion and Treg cell function.
