IL-21 Enhances Phagocytosis in Mononuclear Phagocyte Cells: Identification of Spleen Tyrosine Kinase as a Novel Molecular Target of IL-21
Bibliographic record
Abstract
The biological significance of the IL-21/IL-21R system in human monocytes/macrophages is not well documented, and the expression of IL-21R is unclear and has been disputed. In this study, we showed for the first time, to our knowledge, that human monocyte-like THP-1 cells expressed the two IL-21R components, CD132 (γc) and IL-21Rα, on their cell surface, as assessed by flow cytometry. Moreover, IL-21 was found to enhance FcR-mediated phagocytosis, but not endocytosis. The ability of IL-21 to enhance phagocytosis was not associated with an increased expression of both IL-21R components at the cell surface, and IL-21 did not act in synergy with IL-15. IL-21 activated spleen tyrosine kinase (Syk), as evidenced by its ability to increase Syk phosphorylation. Using a pharmacological approach to inhibit Syk activity, and an antisense technique to downregulate Syk protein expression, we demonstrated the importance of Syk in IL-21-induced phagocytosis. In addition, both CD132 and IL-21Rα were expressed on the cell surface of naive monocytes, as well as in GM-CSF-monocyte-derived macrophages. Moreover, IL-21 also induced phagocytosis in these cells. We conclude that IL-21 possesses important biological effects in mononuclear phagocyte cells and that Syk is a novel molecular target of IL-21 that was previously unknown. Therefore, future development of therapeutic strategies targeting the IL-21/IL-21R system should consider that monocyte and macrophage cell physiology may be affected by this system.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".