Anti-Mouse CD28 (Clone E18) – FITC

CD28 -/- mice were alternately immunized with A20 cells expressing mCD28 and recombinant mCD28Ig

This Fluorescein (FITC) conjugate is formulated in 0.01 M phosphate buffered saline (150 mM NaCl) PBS pH 7.4, 1% BSA and 0.09% sodium azide as a preservative.

Liquid

This Fluorescein conjugate is stable when stored at 2-8°C. Do not freeze.

Research Use Only

2 – 8° C Wet Ice

Blue Laser (488 nm)

E18 activity is directed against mouse CD28 at an epitope close to the B7 binding site.

CD28 is a 44 kD glycoprotein and member of the Ig superfamily that produces co-stimulatory signals necessary for T cell activation and survival as part of the B7-1/B7-2–CD28/CTLA-4 pathway¹. The two B7 family proteins, B7-1 (CD80) and B7-2 (CD86), 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 (IL-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.

E18 was generated by alternately immunizing CD28^-/- mice with A20 cells expressing mCD28 and recombinant mCD28Ig². Splenic cells were fused with X63Ag8.653 for hybridoma production. E18 completely blocks CD28 ligation by B7 molecules³. Additionally, E18 enhances anti-CD3-induced proliferation of peripheral T cells. In vivo, E18 acts as an inhibitor of CD28 signaling and causes a reversible reduction in Treg cell frequencies among CD4⁺ cells.

CD28 is constitutively expressed on the surface of T cells.

CD80 (B7-1), CD86 (B7-2), GRB2, PIK3R1, PRKCQ

1. Sharpe AH, Freeman GJ. Nat Rev Immunol. 2(2):116-126. 2002.
2. Dennehy KM, Elias F, Zeder-Lutz G, et al. J Immunol. 176(10):5725-5729. 2006.
3. Beyersdorf N, Ding X, Blank G, et al. Blood. 112(10):4328-4336. 2008.
4. Langenhorst D, Haack S, Göb S, et al. Front Immunol. 9:1060. 2018.
5. Gladow N, Hollmann C, Ramos G, et al. PLoS One. 15(4):e0227734. 2020.