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ADCP (Antibody-dependent cellular phagocytosis) is a crucial mechanism of immune clearance. Upon binding of a therapeutic monoclonal antibody (mAb) to a target cell, the antibody's Fc region is recognized by Fcγ receptors (FcγRs) on the surface of phagocytic immune cells (such as macrophages, monocytes, and neutrophils), thereby mediating the phagocytic clearance of the target cell. In humans, the FcγR family comprises activating receptors (e.g., FcγRIIa/CD32a, FcγRI/CD64, FcγRIIIa/CD16a) and the inhibitory receptor FcγRIIb (CD32b). FcγRIIb is the only inhibitory Fcγ receptor expressed on the surface of immune cells; its cytoplasmic domain contains an immunoreceptor tyrosine-based inhibitory motif (ITIM). When FcγRIIb binds to the antibody Fc region and undergoes cross-linking, the ITIM becomes phosphorylated and recruits the SH2 domain-containing inositol phosphatase (SHIP), which subsequently inhibits downstream activating signaling pathways, thereby negatively regulating ADCP and other effector functions. FcγRIIb plays a pivotal role in maintaining immune homeostasis and preventing excessive inflammatory responses, while also serving as a significant potential target in cancer immunotherapy and the development of antibody-based drugs.

The ADCP bioassay model—utilizing effector cells expressing FcγRIIb and an NFAT-driven reporter system in Jurkat cells—effectively simulates the ADCP signaling transduction process *in vivo*.

 
Figure 1. Recombinant ADCP Bioassay Effector Cell FcγRIIb-NFAT Jurkat stably expressing FcγRIIb.

Figure 2. Dose Response of Rituximab in ADCP Bioassay Effector Cell FcγRIIb -NFAT Jurkat(C30).

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.