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Members of the Leukocyte Immunoglobulin-like Receptor B (LILRB) family act as negative regulators of myeloid cell activation. LILRBs are Type I transmembrane glycoproteins that function as immunosuppressive receptors; currently identified members of the LILRB family include LILRB1, LILRB2, LILRB3, LILRB4, and LILRB5.

LILRB2 (also known as ILT4) comprises four extracellular Ig domains, a single transmembrane domain, and three ITIM motifs. LILRB2 is predominantly expressed by myeloid cells and serves as a primary inhibitory receptor for myeloid-derived suppressor cells (MDSCs). LILRB2 expression is primarily observed in basophils, monocytes, macrophages, dendritic cells (DCs), and hematopoietic stem cells. Additionally, LILRB2 is expressed in endothelial cells, decidual macrophages, osteoclasts, and neurons.

Ligands for LILRB2 include Class I proteins CD1c and CD1d, angiopoietin-like proteins, Nogo receptor ligands, and beta-amyloid peptides. Upon ligand binding, LILRB2 transduces negative signals through the association of its ITIM motifs with the phosphatase SHP-1.

The Jurkat E6.1 Human LILRB2 Effector Reporter Cell Model—effectively simulates the signal transduction process of  LILRB2 *in vivo*. The underlying principle is illustrated in the figure below.

Figure 1. Schematic Diagram of the Jurkat E6.1 Human LILRB2 Effector Reporter Cell Model

Figure 2. Recombinant LILRB2 Effector Reporter Cell stably expressing LILRB2.

Figure 3.Dose Response of LILRB2 Blocking Antibody in LILRB2 Effector Reporter Cell (C24) with B2M-associated HLA-G/aAPC Cell(C15). Dose Response of LILRB2 Blocking Antibody in LILRB2 Effector Reporter Cell (C24) with B2M-free HLA-G/aAPC Cell.

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.