Calreticulin is an interleukin-3-sensitive calcium-binding protein in human basophil leukocytes
Article first published online: 23 SEP 2008
Volume 56, Issue 1, pages 21–28, January 2001
How to Cite
Lyngholm, M. J., Nielsen, H. V., Holm, M., Schiøtz, P. O. and Johnsen, A. H. (2001), Calreticulin is an interleukin-3-sensitive calcium-binding protein in human basophil leukocytes. Allergy, 56: 21–28. doi: 10.1034/j.1398-9995.2001.00115.x
- Issue published online: 23 SEP 2008
- Article first published online: 23 SEP 2008
- Accepted for publication 25 August 2000
- calcium-binding proteins;
Background: IL-3 enhances basophil histamine release upon stimulation with any known secretagogue. The molecular mechanism behind this regulation is not known, although some observations suggest that IL-3 modulates the calcium part of the signal transduction mechanism. The inhibitory action of glucocorticoids on basophils can be reversed by stimulation with IL-3.
Methods: Calcium-binding proteins in the basophil cell line KU812 were identified by two-dimensional gel electrophoresis, Calcium-overlay assay, N-terminal sequence analysis, and mass spectometry. The presence of the same proteins in purified human basophil leukocytes was established by comigration of KU812 and human basophil proteins on the two-dimensional gels. The expression of the calcium-binding proteins in the absence and presence of IL-3 and/or anti-IgE was determined by densitometric measurement of the spots on the two-dimensional gels.
Results: Calreticulin was identified on the two-dimensional gel of KU812 proteins. A protein with exactly the same migration pattern was found on the gels of proteins from purified human basophils. Immunoblotting with a specific anti-human calreticulin antibody confirmed that this protein was calreticulin. Subsequent analysis showed that the expression of calreticulin in the basophils is upregulated twofold upon stimulation with rhIL-3, even in doses below those needed for enhancement of histamine release.
Conclusions: The expression of calreticulin in human basophil leukocytes is regulated by IL-3. Calreticulin is known to modulate IP3-dependent Ca2+ influx in different cell systems, and calreticulin overexpression inhibits steroid-induced transcriptional activation. Therefore, modulation of calreticulin expression may be one mechanism by which IL-3 exerts its effects on human basophils.