Related Experiment Videos
Orientation of PMN in a pH gradient: acid-induced release of a chemotactic factor
Abstract:
Human and rabbit PMN, placed in a gradient of pH 5 to pH 8 over 1 mm, orient their locomotion toward pH 5. This orientation is due to the release or production of a chemotactic factor by the cells in the acid pH. This activity can be recovered in the supernatant and is maximal when the cell incubation is at pH 5.5. Its appearance is rapid, occurring within 1 min, and is temperature dependent. Cells survive treatment at pH 5.5 and are capable of subsequently responding to chemotactic peptides.
Insights
Human and rabbit polymorphonuclear leukocytes (PMN) move towards acidic pH 5, driven by a pH-induced chemotactic factor. This factor appears rapidly and is temperature-dependent, with cells remaining viable.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- Polymorphonuclear leukocytes (PMN) are crucial immune cells involved in inflammatory responses.
- Cellular responses to environmental stimuli, such as pH gradients, are fundamental to immune cell function.
- Understanding PMN behavior in different pH conditions is vital for studying inflammation and infection.
Purpose of the Study:
- To investigate the behavior of human and rabbit PMN in response to a pH gradient.
- To identify the mechanism driving PMN orientation in acidic environments.
- To characterize the nature and kinetics of the chemotactic factor involved.
Main Methods:
- Human and rabbit PMN were subjected to a pH gradient ranging from 5 to 8 over 1 mm.
- Chemotactic activity in the supernatant was measured after cell incubation at varying pH levels.
- The time course and temperature dependence of the chemotactic factor's appearance were assessed.
- Cell viability and subsequent response to chemotactic peptides were evaluated after pH treatment.
Main Results:
- PMN consistently oriented their locomotion towards the acidic end (pH 5) of the gradient.
- A chemotactic factor, released or produced by PMN in acidic conditions, was identified in the supernatant.
- Chemotactic activity was maximal when cells were incubated at pH 5.5.
- The factor's appearance was rapid (within 1 minute) and temperature-dependent.
- PMN remained viable after exposure to pH 5.5 and retained their ability to respond to chemotactic peptides.
Conclusions:
- PMN exhibit directed migration towards acidic pH, mediated by a self-produced chemotactic factor.
- The acidic pH triggers a rapid release or production of this factor, influencing PMN behavior.
- This pH-dependent chemotaxis is a significant factor in PMN function during inflammatory processes, with cells maintaining viability.