Anti-Mouse CD28 [Clone D665] - Purified <i>in vivo</i> PLATINUM™ Functional Grade (C2513-25mg)

The B7-1/B7-2–CD28/CTLA-4 pathway is a T cell co-stimulatory pathway crucial to T cell activation and tolerance1. The pathway includes two B7 family proteins, B7-1 (CD80) and B7-2 (CD86), that have dual specificity for the stimulatory receptor CD28 and the inhibitory receptor CTLA-4 (CD152). When B7-1 and B7-2 interact with CD28, an important co-stimulatory signal, transmitted via CD28, synergizes with the TCR signal to regulate the threshold for T cell activation and promote T cell survival, clonal expansion, and differentiation. CD28 also promotes interleukin-2 production. In contrast, when B7-1 and B7-2 engage with CTLA-4, a negative signal inhibits TCR- and CD28-mediated signaling as well as IL-2 synthesis, and the T cell response is terminated. D665 was generated by immunizing CD28 -/- mice (B6.129S2-Cd28 tm1Mak/J) alternatively with A20 cells expressing murine CD28 and recombinant murine CD28Ig2. Spleen cells were fused with X63Ag8.653 cells and antibody was captured at 51-53 resonance units on an anti-mouse coated CM5 sensor surface. D665 is considered a CD28-superagonist and can be used to activate and expand T cells, including Tregs2,3,4,5 and type 1 regulatory T cells6,7, in vitro. D665 predominately ligates CD28 bivalently at low CD28/antibody ratios and induces Ag-independent T cell proliferation2. The D665 epitope resides in the C′D loop of mCD28, and grafting a human C′D loop to mCD28 severely diminishes binding. D665 is being investigated as a potential agonistic therapy for ulcerative colitis6,8, pemphigus vulgaris9, and allograft rejection7.