References: Lucy S. K. Walker, Helen E. Wiggett, Fabrina M. C. Gaspal, Chandra R. Raykundalia, Margaret D. Goodall, Kai-Michael Toellner, and Peter J. L. Lane. 2003. Established T Cell-Driven Germinal Center B Cell Proliferation Is Independent of CD28 Signaling but Is Tightly Regulated Through CTLA-4. J Immunol. 170:91-98.
Kohyama M, Sugahara D, Sugiyama S, Yagita H, Okumura K, Hozumi N. Inducible costimulator-dependent IL-10 production by regulatory T cells specific for self-antigen. Proc Natl Acad Sci U S A. 2004 Mar 23;101(12):4192-7. (blocking, PubMed)
McAdam AJ, Chang TT, Lumelsky AE, Greenfield EA, Boussiotis VA, Duke-Cohan JS, Chernova T, Malenkovich N, Jabs C, Kuchroo VK, Ling V, Collins M, Sharpe AH, Freeman GJ. Mouse inducible costimulatory molecule (ICOS) expression is enhanced by CD28 costimulation and regulates differentiation of CD4+ T cells. J Immunol. 2000 Nov 1;165(9):5035-40.