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LAIR1 (Leukocyte-Associated Immunoglobulin-like Receptor 1) is a critical inhibitory immune checkpoint receptor belonging to the immunoglobulin superfamily (IgSF). It transmits inhibitory signals by recognizing collagen within the extracellular matrix (ECM)—specifically the GPO repeat sequences found in the alpha chains of Type I and Type III collagen—thereby participating in the maintenance of immune homeostasis, the suppression of autoimmunity, and tumor immune evasion. LAIR1 is a single-chain transmembrane glycoprotein; its extracellular domain contains a single Ig C2-type domain, undergoes N-glycosylation, and binds with high affinity to the Gly-X-Y repeat sequences of collagen as well as the collagen-like regions of complement factor C1q. The transmembrane region consists of 20 amino acids, while the intracellular domain contains two Immunoreceptor Tyrosine-based Inhibitory Motifs (ITIMs), which recruit the phosphatases SHP-1 and SHP-2 to transduce inhibitory signals.

As a co-inhibitory receptor, LAIR1 is widely expressed on T cells, B cells, NK cells, monocytes, and dendritic cells; by binding to its ligands, it inhibits the activation, proliferation, and cytokine secretion of immune cells. Its signal transduction pathway functions by suppressing cascades such as the JAK/STAT and PI3K/AKT/mTOR pathways, thereby regulating the expression of cell cycle proteins (e.g., cyclin D1) and apoptosis-related proteins (e.g., Bcl-2 and BAX).

The Jurkat E6.1 Human LAIR1 Effector Reporter Cell Model—effectively simulates the signal transduction process of LAIR1 *in vivo*. The underlying principle is illustrated in the figure below.

Figure 1. Schematic Diagram of the C Jurkat E6.1 Human LAIR1 Effector Reporter Cell  Model

Figure 2. Recombinant LAIR1 Effector Reporter Cell stably expressing LAIR1.

Figure 3. Dose Response of LAIRl Agonist Ab in LAIR1 Effector Reporter Cell(C27).

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.