Related Experiment Videos
Mitogen-activated Ca++ channels in human B lymphocytes
1Department of Medicine, Hahnemann University, Philadelphia, Pennsylvania 19102.
Journal of Cellular Physiology
|June 1, 1993
Summary
Human B cell activation involves calcium influx through transmembrane potential-sensitive channels. These channels, regulated by inositol trisphosphate (IP3), are crucial for early B cell activation stages.
Area of Science:
- Immunology
- Cell Biology
- Biophysics
Background:
- Human B cell activation is a complex process involving changes in intracellular calcium levels.
- Mitogen-induced transmembrane conductances play a role in regulating calcium influx during B cell activation.
Purpose of the Study:
- To investigate mitogen-induced transmembrane conductances in human B cells (Daudi cell line).
- To elucidate the role of calcium influx and transmembrane potential in early B cell activation.
Main Methods:
- Spectrofluorometry to measure intracellular calcium ([Ca++]i) and transmembrane potential.
- Voltage clamp techniques to analyze membrane currents in Daudi cells.
- Activation using anti-mu antibodies and inositol trisphosphate (IP3).
Main Results:
- Anti-mu antibody stimulation caused a biphasic rise in [Ca++]i, with the second phase due to extracellular calcium influx.
- Calcium influx was sensitive to transmembrane potential and inhibited by high extracellular potassium.
- Voltage clamp revealed inward currents activated by anti-mu antibodies and IP3, blocked by lanthanum, indicating Ca++ channel activity.
- IP3 activation suggested a role for IP3 generation in conductance activation.
Conclusions:
- Human B cells possess membrane calcium channels critical for early activation stages.
- Transmembrane potential changes regulate calcium influx during B cell activation.
- These mechanisms collectively control intracellular calcium levels in early B cell activation.