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Updated: Jul 5, 2026
Measuring Phagosome pH by Ratiometric Fluorescence Microscopy
Published on: December 7, 2015
Acidification enhances peritoneal macrophage phagocytic activity
Julia E Grabowski1, Virginia L Vega, Mark A Talamini
1Department of Surgery, University of California, San Diego, San Diego, California.
Background:
Laparoscopic surgery is currently used in an array of diverse clinical situations, including cases with potential bacterial contamination. Previous studies have shown that CO2 insufflation during laparoscopic procedures modulates the immune response due to the acidification of the peritoneum. In the present study, we investigated whether exposure of macrophages to an acidic environment, such as that produced by CO2 insufflation, could affect phagocytosis, which is the fundamental process for bacterial clearance.
Materials And Methods:
A murine peritoneal macrophage line (J774) was pre-incubated at pH levels of 6.0 or 7.4 for 3 h at 37 degrees C and returned to neutral pH (7.4). Phagocytosis was evaluated by incubation with fluorescein isothiocyanate-conjugated IgG-opsonized bacterial particles, IgG-opsonized fluorescent latex beads, and non-opsonized fluorescent latex beads at 37 degrees C, pH 7.4. The intensity of the internalized signal was measured by using a fluorometer.
Results:
Pre-incubation of macrophages at a pH of 6.0 resulted in a significant increase of phagocytic activity of opsonized particles. However, it did not change the uptake of non-opsonized particles. This effect was due to the internalization process since there were no differences in foreign particle binding of cells exposed to acidic or neutral pH levels.
Conclusions:
This study demonstrates that environmental acidification increases the phagocytosis of opsonized particles by macrophages. These results suggest that CO2 insufflation during laparoscopic surgery may be beneficial for the clearance of pathogens, particularly in cases where there is a high risk of potential intra-abdominal infections.
Insights
Acidic environments enhance macrophage phagocytosis of opsonized particles. This suggests carbon dioxide (CO2) insufflation during laparoscopic surgery may improve bacterial clearance and reduce infection risk.
Area of Science:
- Immunology
- Surgical Innovation
- Cell Biology
Background:
- Laparoscopic surgery often involves CO2 insufflation, leading to peritoneal acidification.
- Acidification is known to modulate immune responses.
- The impact of acidic environments on macrophage phagocytosis remains unclear.
Purpose of the Study:
- To investigate the effect of an acidic environment on macrophage phagocytosis.
- To determine if CO2-induced acidification influences bacterial clearance mechanisms.
Main Methods:
- Murine macrophages (J774) were exposed to pH 6.0 or 7.4.
- Phagocytosis assays used opsonized bacterial particles and latex beads.
- Internalization was quantified using fluorescence measurements.
Main Results:
- Pre-incubation at pH 6.0 significantly increased macrophage phagocytosis of opsonized particles.
- No significant change in the uptake of non-opsonized particles was observed.
- Acidification enhanced particle internalization, not surface binding.
Conclusions:
- Environmental acidification boosts macrophage phagocytosis of opsonized targets.
- CO2 insufflation during laparoscopy may enhance pathogen clearance.
- This mechanism could be beneficial in preventing intra-abdominal infections.
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