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Updated: Jul 16, 2026

An ELISA Based Binding and Competition Method to Rapidly Determine Ligand-receptor Interactions
Published on: March 14, 2016
Soluble Interleukin IL-15Ralpha is generated by alternative splicing or proteolytic cleavage and forms functional
Elena Bulanova1, Vadim Budagian, Erwin Duitman
1Department of Immunology and Cell Biology and Immunochemistry and Biochemical Microbiology, Research Center Borstel, Borstel D-23845, Germany. ebulanova@fz-borstel.de
Interleukin 15 (IL-15) forms complexes with soluble IL-15 receptor alpha (IL-15Ralpha) in mice, affecting its detectability. Two IL-15Ralpha isoforms regulate IL-15 activity through distinct mechanisms.
Area of Science:
- Immunology
- Molecular Biology
- Cytokine Signaling
Background:
- Interleukin 15 (IL-15) is a crucial cytokine involved in immune responses.
- IL-15 is typically undetectable in biological fluids using standard assays like ELISA.
- The role of IL-15 receptor alpha (IL-15Ralpha) in IL-15 bioavailability and function requires further elucidation.
Purpose of the Study:
- To investigate the formation of IL-15 heterocomplexes in biological fluids.
- To identify and characterize soluble IL-15Ralpha (sIL-15Ralpha) isoforms and their generation mechanisms.
- To determine the functional impact of different sIL-15Ralpha forms on IL-15 activity.
Main Methods:
- Analysis of IL-15 and IL-15Ralpha complexes in mouse serum and cell-conditioned medium.
- Identification of sIL-15Ralpha isoforms using alternative splicing analysis.
- Functional assays assessing IL-15-mediated cell proliferation (CTLL cell line) and cytokine production (murine NK cells).
- Investigation of proteolysis by tumor necrosis factor-alpha-converting enzyme (TACE) on full-length IL-15Ralpha.
Main Results:
- IL-15 forms functional heterocomplexes with soluble high-affinity IL-15Ralpha, hindering ELISA detection.
- Two sIL-15Ralpha sushi domain isoforms are generated via alternative splicing, enhancing IL-15 action.
- These isoforms promote CTLL cell proliferation and interferon gamma production by NK cells, indicating a role in IL-15 transpresentation.
- A full-length sIL-15Ralpha ectodomain, released by TACE-dependent proteolysis, inhibits IL-15 activity.
Conclusions:
- A dual mechanism governs sIL-15Ralpha generation in mice, producing polypeptides with opposing effects on IL-15 function.
- These findings reveal novel regulatory pathways for IL-15 bioavailability and activity through soluble receptor interactions.
- Understanding these mechanisms is critical for comprehending IL-15-mediated immune regulation and potential therapeutic interventions.
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