IL-33 stands for interleukin 33. Human IL-33 is a recombinant protein optimized for use in cell culture, differentiation studies, and functional assays.

Specifications for Human IL-33


IL-33 stands for interleukin 33. Human IL-33 is a recombinant protein optimized for use in cell culture, differentiation studies, and functional assays.


Human IL-33 can be used for a variety of applications, including:
  • Tʜ2 cell activation and maintenance.
  • Investigation of intracellular signaling of IL-1 family and apoptotic/necrotic pathways.
  • In vitro inhibition of osteoclast differentiation.

Detailed product information

Background information

Interleukin 33 (IL-33) is a cytokine belonging to the IL-1 family. Similarly to other IL-1 family members, IL-33 exists in both an un-cleaved (full-length) and a cleaved form, although the proteins responsible of IL-33 maturation are still under investigation. IL-33 is expressed by several cell types including epithelial cells, endothelial cells, and fibroblasts, and binds a specific receptor, also known as IL1RL1, which is expressed on Tʜ2 cells and mast cells. Signaling via IL1RL1 involves receptor accessory protein (IL1RAP) and leads to the expression of type 2 cytokines, such as IL-4, IL-5, IL-13. Via enhancing the activation of Tʜ2 cells, mast cells, and eosinophils, IL-33 sustains the humoral response and contributes to adverse Tʜ2 reactions, such as dermatitis, asthma, and allergies. Besides its primary involvement in the immune system modulation, IL-33 is also expressed in blood epithelium and smooth muscle and plays a role in bone protection. It is unclear whether also the immature form of IL-33 could be biologically active after release, such as during necrosis. Moreover, it was suggested that the full length protein could co-localize in the nucleus and act as transcriptional factor. Recombinant Human IL-33 corresponds to the mature form of human IL-33.

Biological activity

  • Proliferation of D10.G4.1 cells
  • research grade: ≥ 4×
  • premium grade: ≥ 8×
  • We measure the biological activity of each batch of MACS Premium-Grade Cytokines and state the results in the Certificate of Analysis (CoA). Based on the lot-specific activity, exact doses of active cytokine can be applied to cell culture experiments. This allows for reproducible cell culture conditions without the need for time-consuming lot-to-lot testing.

Quality description

cytokines are suitable for a wide variety of cell culture applications. They are sterile-filtered prior to lyophilization. Generally, endotoxin levels are <0.1 ng/μg (<1 EU/μg), and purities are >95%. The biological activity is tested in appropriate bioassays.
cytokines offer the convenience of high and well-defined biological activities and allow exact unit dosing for demanding applications. The biological activity is determined after lyophilization and reconstitution, and normalized to WHO/NIBSC standards whenever available. In general, endotoxin levels are <0.01 ng/μg (<0.1 EU/μg), and purities are >97%. Lot-specific activities are stated in the Certificate of Analysis (www.

Resources for Human IL-33

Documents and Protocols


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References for Human IL-33


  1. Campana, S. et al. (2021) Circulating ILC precursors expressing CD62L exhibit a type 2 signature distinctly decreased in psoriatic patients. Eur J Immunol. 51(7): 1792-1798
  2. Dilasser, F. et al. (2021) Essential role of smooth muscle Rac1 in severe asthma-associated airway remodelling. Ther Clin Risk Manag 76(4): 326-334

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