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Regulation of cytoplasmic pH in phagocytic cell function and dysfunction.
S Grinstein1, C J Swallow, O D Rotstein
1Division of Cell Biology, Hospital for Sick Children, Toronto, Canada.
Clinical Biochemistry
|June 1, 1991
Summary
Phagocytic cells regulate cytoplasmic pH (pHi) using ion transport systems. Acidic environments can overwhelm these mechanisms, impairing cell function and abscess resolution.
Area of Science:
- Immunology
- Cell Biology
- Physiology
Background:
- Phagocytic cells, like neutrophils and macrophages, require optimal cytoplasmic pH (pHi) for antimicrobial and tumoricidal functions.
- Intracellular enzyme activity is critically dependent on maintaining a specific pHi range.
- Dysregulation of pHi can compromise phagocyte function.
Purpose of the Study:
- To review the mechanisms of cytoplasmic pH regulation in phagocytic cells.
- To explore how acidic microenvironments, such as those in abscesses, impact phagocyte pHi.
- To understand the consequences of cytoplasmic acidification on phagocyte function and abscess resolution.
Main Methods:
- Review of existing literature on ion transport systems in phagocytes.
- Analysis of mechanisms for pHi regulation, including Na+/H+ exchange and chloride/bicarbonate exchange.
- Examination of ATP-dependent proton extrusion mechanisms (vacuolar-type H+ ATPase).
Main Results:
- Phagocytes utilize both bicarbonate-independent (e.g., Na+/H+ exchanger) and bicarbonate-dependent (chloride/bicarbonate exchange) systems to regulate pHi.
- Macrophages also employ an ATP-dependent proton pump for pHi recovery.
- Acidic microenvironments in abscesses can lead to cytoplasmic acidification, overwhelming regulatory mechanisms.
Conclusions:
- Cytoplasmic acidification impairs neutrophil migration and respiratory burst activity.
- Impaired phagocyte function due to acidification can hinder complete abscess resolution.
- Understanding pHi regulation is crucial for addressing infections and inflammatory conditions involving phagocytes.