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Updated: Aug 8, 2026
Generation of Human CD40-activated B cells
Published on: October 17, 2009
Induction of CD25 expression in human B lymphocytes by pharmacological activators of cellular signalling pathways
1Division of Biochemistry & Molecular Biology, Institute of Biomedical & Life Sciences, University of Glasgow, UK.
Insights
Interleukin-4 (IL-4) upregulates CD23 and CD25 antigens on B cells. This process involves protein kinase C activation and calcium mobilization, suggesting a shared signaling pathway for both markers.
Area of Science:
- Immunology
- Cell Biology
- Molecular Signaling
Background:
- Interleukin-4 (IL-4) is a key cytokine in immune regulation.
- B lymphocytes express CD23 and CD25 antigens, which are important for immune responses.
- Understanding the signaling pathways of IL-4 is crucial for developing targeted immunotherapies.
Purpose of the Study:
- To investigate the dose-dependent effects of IL-4 on CD23 and CD25 expression in human B lymphocytes.
- To elucidate the intracellular signaling mechanisms, including calcium mobilization and protein kinase C involvement, underlying IL-4-induced antigen expression.
- To compare the signaling pathways of IL-4 with those of other B cell activation stimuli.
Main Methods:
- Three-color flow cytometry was used to analyze antigen expression on B cells.
- Dose-response experiments with IL-4 were performed.
- Pharmacological agents like phorbol ester, ionomycin, forskolin, and BAPTA were used to probe signaling pathways.
- Protein kinase C activity was modulated using phorbol ester treatments.
Main Results:
- IL-4 induced simultaneous expression of CD23 and CD25 in a dose-dependent manner.
- CD23 induction by IL-4 required lower doses than CD25 induction.
- Pharmacological agents mimicked IL-4's effect, involving intracellular calcium mobilization and protein kinase C activation.
- Down-regulation of protein kinase C abolished IL-4's ability to upregulate CD23 and CD25.
Conclusions:
- IL-4 utilizes a common signal transduction pathway involving protein kinase C and cAMP for CD23 and CD25 expression.
- Intracellular calcium mobilization is essential for IL-4-mediated CD25 expression.
- The findings provide insights into B cell activation and regulation by IL-4.
Abstract:
IL-4 promotes simultaneous expression of both the CD23 and CD25 antigens in resting human B lymphocytes in a dose-dependent manner. Simultaneous three-colour flow cytometric analysis revealed that CD19+/CD23+/CD25+ triple-positive cells were derived from a CD19+/CD23-/CD25- pool, and that induction of CD23 required lower doses of IL-4 than did induction of CD25. Although the concentrations of IL-4 required for half-maximal up-regulation of CD23 (35 pM) and CD25 (150 pM) expression were different, the capacity of IL-4 to promote expression of the two markers could be mimicked by the same combination of pharmacological agents. Thus, maximal expression of CD23 and CD25 was obtained with a 30 (or 120) second pulse with phorbol ester and/or ionomycin followed by a sustained (20 minute) treatment with forskolin. Use of BAPTA to chelate intracellular calcium suggested that IL-4 driven CD25 expression required mobilization of intracellular Ca2+. Finally, down-regulation of cellular protein kinase C by chronic treatment of resting B lymphocytes with phorbol ester abolished the ability of IL-4 to elevate CD23 and CD25 expression; phorbol ester treatment similarly abrogated the ability of anti-CD40 and anti-Ig reagents to promote expression of CD25. The data are consistent with the proposal that IL-4 influences CD23 and CD25 expression via a similar signal transduction pathway which involves both protein kinase C activation and elevation of intracellular cAMP levels.
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