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ICOS is a co-stimulatory receptor whose expression is induced only following T-cell activation, while ICOSL—its corresponding ligand—is constitutively expressed primarily on the surface of B cells and antigen-presenting cells. The core principle of action for this pair lies in the fact that when activated T cells (particularly follicular helper T cells) migrate into lymphoid follicles and encounter B cells, the binding of ICOS to ICOSL delivers critical co-stimulatory signals to the T cells. This process, mediated primarily through the activation of downstream pathways such as PI3K, drives T-cell proliferation, survival, and cytokine production (e.g., IL-21). Consequently, it precisely regulates the germinal center reaction, ultimately facilitating B-cell antibody affinity maturation and class switching, thereby generating a robust humoral immune response.

The ICOS Effector Reporter Cell model serves as an excellent mimic of the in vivo ICOS signal transduction process; the underlying principle is illustrated in the figure below.

Figure 1. Schematic Diagram of the Jurkat E6.1 Human ICOS Effector Reporter Cell Cell Model

Figure 2. Recombinant ICOS Effector Reporter Cell stably expressing ICOS.

Figure 3. Dose Response of ICOS Agonist Abs in ICOS Effector Reporter Cell(C3) with FCGR2B TCR Activitor CHO(C18).

Figure 4. Blocking of ICOSL induced ICOS Effector Reporter Cell(C3) Activity by ICOSL Blocking Ab with ICOSL aAPC CHO(C42).

Cell Passage Procedures

1.This cell line grows in suspension.
2.Upon receipt, cells should be thawed immediately or stored in liquid nitrogen until use.
3.Before thawing, pre-warm the water bath and culture medium to 37 °C, and prepare a small amount of dry ice.
4.Remove the cryovial from storage and transport it to the cell culture laboratory on dry ice.
5.Rapidly thaw the cells in a 37 °C water bath. Once the cells are completely thawed, spray the cryovial with 70% ethanol for disinfection and transfer it to a biosafety cabinet.
6.Add 10 mL of pre-warmed culture medium into a 15 mL centrifuge tube. Transfer the contents of the cryovial into the tube and centrifuge at 1000 rpm for 5 minutes.
7.Carefully discard the supernatant. Resuspend the cell pellet in 5 mL of pre-warmed culture medium by gentle pipetting. Immediately perform cell counting and adjust the cell density to 3–6 × 10⁵ cells/mL based on the counting results, then transfer the cells into a culture flask.
8.Count the cells every 1–2 days. When the cell density exceeds 1 × 10⁶ cells/mL, passage the cells promptly or add fresh culture medium. Maintain the cell density between 2 × 10⁵ and 1 × 10⁶ cells/mL.

Suspension Cell Cryopreservation Procedure:

1.Collect 8 × 10⁶ cells, centrifuge, and discard the supernatant.
2.Add 1 mL of cell freezing medium (90% FBS + 10% DMSO) and gently pipette to mix thoroughly. Transfer the suspension into a cryovial.
3.Immediately place the cryovial into a controlled-rate freezing container (Nalgene 5100-0001), fill with isopropanol up to the indicated level, and store at −80 °C.
4.After 24 hours, transfer the cryovial to liquid nitrogen for long-term storage.