Related Experiment Videos
Effect of okadaic acid on human basophil secretion
1Johns Hopkins Asthma and Allergy Center, Baltimore, MD 21224.
Biochemical Pharmacology
|June 9, 1993
Summary
Okadaic acid, a phosphatase inhibitor, significantly blocked immunoglobulin E (IgE)-mediated histamine and leukotriene release from human basophils. However, it did not affect fMet-Leu-Phe peptide-stimulated secretion or calcium ion levels.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Human basophils release mediators upon stimulation via distinct biochemical pathways.
- Phosphatase activity plays a role in regulating mediator secretion.
Purpose of the Study:
- To investigate the effect of okadaic acid, a phosphatase inhibitor, on mediator secretion from human basophils.
- To determine if okadaic acid influences calcium signaling pathways involved in basophil activation.
Main Methods:
- Human basophils were preincubated with varying concentrations of okadaic acid.
- Cells were stimulated with anti-IgE antibody or fMet-Leu-Phe peptide.
- Histamine and leukotriene release were measured.
- Cytosolic calcium ion concentrations were monitored.
Main Results:
- Okadaic acid (1 microM) inhibited IgE-mediated histamine release by 80% and leukotriene release by 100%.
- Inhibition was concentration-dependent, with lower concentrations showing less effect.
- Okadaic acid did not inhibit secretion stimulated by fMet-Leu-Phe peptide.
- Okadaic acid did not affect cytosolic calcium elevations induced by either stimulus.
Conclusions:
- Phosphatase inhibition by okadaic acid selectively blocks IgE-mediated mediator release from human basophils.
- The mechanism of inhibition does not involve modulation of cytosolic calcium levels.
- Okadaic acid's effects differ from cAMP-active agents in modulating basophil activation pathways.