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Interleukin (IL)-4 and Interleukin (IL)-13 are related cytokines that regulate many aspects of allergic inflammation. They play significant roles in modulating the responses of lymphocytes, myeloid cells, and non-hematopoietic cells. IL-4 and IL-13 are hallmark cytokines of Type 2 inflammatory responses. They serve as key participants in the inflammatory reactions triggered by invading parasites or allergens.

IL-4 is a glycosylated Type I cytokine primarily produced by T cells, natural killer T (NKT) cells, mast cells, and eosinophils. IL-4 initiates signal transduction through one of two distinct receptor complexes: a Type I receptor expressed on hematopoietic cells, or a Type II receptor expressed on non-hematopoietic cells. The Type I receptor consists of the IL-4Rα subunit and the common gamma chain (IL-2Rγ subunit) and is specific for IL-4; conversely, the Type II receptor comprises the IL-4Rα and IL-13Rα1 subunits and can be activated by either IL-4 or IL-13.

The binding of IL-4 to its receptor leads to the activation of the Janus kinase (JAK) family and the phosphorylation of IL-4Rα. STAT proteins are phosphorylated by JAKs to form homodimers, which then translocate to the nucleus to initiate IL-4/IL-13 gene transcription and regulate the expression of genes such as CD23. IL-4 has been considered a therapeutic target for promoting and redirecting T-cell and B-cell functions; however, the use of IL-4 itself has been problematic—particularly due to the deleterious side effects associated with the activation of Type II IL-4 receptors in non-hematopoietic cells. IL-4 signaling is essential for the differentiation of Th2 and Th9 cells and regulates immunoglobulin class switching in B cells. Furthermore, IL-4 promotes the survival and proliferation of mast cells and induces the chemotaxis of mast cells, basophils, and eosinophils, thereby playing a central role in the development of allergic inflammation and asthma.

The HEK293 Human IL4/IL13 Effector Reporter Cell Model—effectively simulates the signal transduction process of IL4/IL13  *in vivo*. The underlying principle is illustrated in the figure below.

Figure 1. Schematic Diagram of the HEK293 Human IL4/IL13 Effector Reporter Cell Model

Figure 2. Dose Response of Recombinant Human IL4/IL13 in IL4/IL13 Dual Effector Reporter Cell(C7).

Figure 3. Inhibition of  IL4/IL13 induced Reporter Activity by IL4R Neutralizing Antibody in IL4/IL13 Dual Effector Reporter Cell(C7).

Cell Resuscitation
1)Rapidly thaw the frozen cells in a 37 °C water bath for approximately 60 seconds. Once thawed (which may take slightly less or more than 60 seconds), immediately transfer the cell suspension from the cryovial into a 15 mL centrifuge tube containing 10 mL of pre-warmed  HEK293 Human IL4/IL13 Effector Reporter Cell complete culture medium.
2)Centrifuge cells at 1000 rpm for 5 min to remove medium, then resuspend cells in 5 mL of pre-warmed complete medium.
3)Transfer the cell suspension into a T25 culture flask and incubate at 37 °C with 5% CO₂.
4)After approximately 24–36 hours, replace the medium or passage the cells to remove non-adherent dead cells.

Subculturing procedure
1)When the cell density reaches the appropriate confluency for passaging, wash the cells with PBS, then add 1 mL trypsin to detach the cells. When more than 80% of the cells detach upon gently tapping the culture flask, add complete culture medium to terminate digestion. Gently pipette to obtain a single-cell suspension, transfer to a 15 mL centrifuge tube, and centrifuge at 1000 rpm for 5 minutes.

2)Discard supernatant after centrifugation. Resuspend cells in fresh medium to a single-cell suspension and transfer to a new culture flask for continued growth.

Cell Freezing
After trypsinization and centrifugation of cells from each T75 flask or 10 cm culture dish, discard the supernatant. Add 2 mL of cryopreservation medium (90% FBS + 10% DMSO), gently resuspend thoroughly, and aliquot into two cryovials. Immediately place the cryovials into a controlled-rate freezing container (e.g., Nalgene 5100-0001), fill with isopropanol to the indicated level, and store at −80 °C. After 24 hours, transfer the cryovials to liquid nitrogen for long-term storage.