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APRIL (A Proliferation-Inducing Ligand; official gene name TNFSF13, also known as CD256) is a member of the tumor necrosis factor (TNF) superfamily. Encoded by the *TNFSF13* gene on chromosome 17, it is a type II transmembrane protein that is secreted as a homotrimer following proteolytic cleavage. APRIL exerts its effects through the high-affinity receptor BCMA and the low-affinity receptor TACI. It is primarily produced by myeloid cells, activated lymphocytes, and mucosal epithelial cells. Its core functions include promoting the differentiation of B cells into plasma cells and maintaining their survival; notably, it drives IgA class switching at mucosal sites and serves as a critical survival factor for long-lived plasma cells.

The CHO-K1 Human APRIL Cell model effectively simulates the in vivo APRIL signal transduction process, the principle is illustrated in the figure below.

Figure 1. Schematic diagram of the CHO-K1 Human APRIL Cell model

Figure 2. Recombinant APRIL CHO stably expressing APRIL.

Figure 3. Blocking of APRIL induced TACI Effector Reporter Cell(C32) Activity by APRIL Blocking Ab with APRIL CHO(C4).

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  CHO-K1 Human APRIL 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.