Related Experiment Videos
Difference in the way of macrophage recognition of target cells depending on their apoptotic states
C Fujii1, A Shiratsuchi, J Manaka
1Graduate School of Natural Science and Technology, Kanazawa University, Takara-machi, Kanazawa, Ishikawa 920-0934, Japan.
Abstract:
Dying cells are selectively eliminated from the organism by phagocytosis. Previous studies suggested the existence of some other phagocytosis marker(s) that function together with phosphatidylserine, the best-characterized phagocytosis marker. We obtained here a monoclonal antibody named PH2 that inhibited macrophage phagocytosis of late apoptotic or necrotic cells, but not of early apoptotic cells. On the other hand, phagocytosis of cells at any time during the process of apoptosis was inhibitable by phosphatidylserine-containing liposomes. Inhibition occurred even when target cells were preincubated with PH2 and separated from unbound antibodies. Moreover, PH2 bound to apoptotic cells at late stages more efficiently than to those at early stages, and it did not bind to normal cells unless their plasma membrane was permeabilized. These results suggest that the putative PH2 antigen is a novel phagocytosis marker that translocates to the cell surface at late stages of apoptosis, resulting in maximal recognition and engulfment by macrophages.
Insights
Researchers identified PH2, a novel phagocytosis marker on late apoptotic cells. This marker aids macrophage recognition and engulfment, working alongside phosphatidylserine to clear dying cells.
Area of Science:
- Cell biology
- Immunology
- Apoptosis research
Background:
- Phagocytosis is crucial for removing dying cells.
- Phosphatidylserine is a known phagocytosis marker.
- Other markers may cooperate with phosphatidylserine.
Purpose of the Study:
- To identify novel phagocytosis markers.
- To characterize the function of the PH2 antibody.
- To understand cell surface changes during apoptosis.
Main Methods:
- Generation of monoclonal antibody PH2.
- Inhibition assays of macrophage phagocytosis.
- Flow cytometry to assess PH2 binding to apoptotic cells.
Main Results:
- PH2 inhibited phagocytosis of late apoptotic/necrotic cells, not early apoptotic cells.
- PH2 binds preferentially to late-stage apoptotic cells.
- PH2 is a novel marker translocating to the cell surface during late apoptosis.
Conclusions:
- PH2 is a novel phagocytosis marker.
- PH2 facilitates macrophage recognition and engulfment of late apoptotic cells.
- PH2 complements phosphatidylserine in the clearance of dying cells.