Related Experiment Video
Updated: Jun 9, 2026
06:15
Quantification of Efferocytosis by Single-cell Fluorescence Microscopy
Published on: August 18, 2018
Decrease of sialic acid residues as an eat-me signal on the surface of apoptotic lymphocytes
Hanna Marie Meesmann1, Eva-Marie Fehr, Sonja Kierschke
1Department of Medicine V, University of Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany.
Journal of Cell Science
|September 10, 2010
Summary
Cell surface glycocalyx changes, specifically reduced sialic acids on apoptotic cells, promote their clearance. Modifying these sugars enhances engulfment, impacting cellular homeostasis.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- Silent clearance of apoptotic cells is crucial for multicellular organism homeostasis.
- While mediators of apoptotic cell recognition are known, distinct mechanisms remain unclear.
Purpose of the Study:
- To investigate alterations in the cell surface glycocalyx of apoptotic cells.
- To determine the impact of these changes on cellular engulfment.
Main Methods:
- Apoptosis was induced in lymphocytes.
- Surface glycocalyx alterations (sialic acids, fucose) on apoptotic cells and membrane blebs were analyzed.
- Engulfment assays were performed after enzymatic treatment (neuraminidase) and lectin binding.
Main Results:
- Apoptotic lymphocytes showed decreased α2,6- and α2,3-linked sialic acids.
- Apoptotic membrane blebs displayed altered sialic acid exposure and increased fucose residues.
- Neuraminidase treatment and sialic acid-binding lectins enhanced engulfment of apoptotic cells and blebs.
- Neuraminidase treatment also increased engulfment of viable lymphoblasts, but not resting viable lymphocytes.
Conclusions:
- The cell surface glycocalyx, particularly terminal sialic acids, plays a significant role in regulating apoptotic cell clearance.
- Changes in surface glycosylation can directly mediate engulfment or enhance phagocytosis through cooperation with other signals, depending on cell type and activation status.
More Related Videos
Related Concept Videos
01:17Phagocytosis of Apoptotic Cells
Cells undergoing apoptosis form apoptotic bodies that must be removed immediately to prevent inflammation, autoimmune diseases, and necrosis. Phagocytosis is carried out by professional phagocytes such as macrophages or immature dendritic cells. Non-professional phagocytes such as epithelial cells and fibroblasts also take part in this process; however, they are not as effective as professional phagocytes.
Normal cells contain receptors that prevent them from being recognized by phagocytes.
Normal cells contain receptors that prevent them from being recognized by phagocytes.
01:17The Extrinsic Apoptotic Pathway
The extrinsic apoptotic pathway is initiated when extracellular death-inducing signals, such as specific cytokines, activate the death receptors expressed on the cell surface. The immune cells involved in this pathway are natural killer cells (NK cells) and cytotoxic T-lymphocytes. NK cells are critical in innate immune response, while cytotoxic T-lymphocytes are associated with adaptive immune response. These cells recognize specific receptors expressed on the altered cells and activate...
01:30Apoptosis
Apoptosis is a combination of two Greek words, 'apo' and 'ptosis,' meaning separation and falling off, respectively. Hippocrates used this word to describe gangrene, which was caused due to bandaging of fractured bones. Apoptosis was distinguished from necrosis in 1970 when John Kerr reported observations of morphological changes occurring during apoptosis. During one experiment, he observed that the disruption of blood supply to the liver tissue resulted in a size reduction of the tissue.
01:11Cellular Injury IlI: Cellular Death
Cell death is the irreversible loss of cellular structure and function, representing the final stage of severe injury. It plays a key role in both normal physiology and disease.Types of Cell DeathThe two main types are necrosis and apoptosis, though others like necroptosis and pyroptosis also exist.Necrosis:Necrosis is an unregulated form of cell death caused by severe injury such as trauma, toxins, or ischemia. It is characterized by cell swelling, membrane loss, rupture, and leakage of...
01:22Cellular Injury V: Apoptosis and Autophagy
Cells respond to damage and stress through highly coordinated processes that decide whether they survive or undergo controlled self-destruction. Two major pathways involved in this regulation are apoptosis, a type of programmed cell death, and autophagy, a survival mechanism that helps cells adapt to adverse conditions.ApoptosisApoptosis removes aged or injured cells to maintain tissue balance. During this process, the cell shrinks, chromatin condenses and fragments, and membrane-bound...
01:28Cells of the Innate Immune Response
The innate immune response is an immediate and non-specific response against pathogens, acting swiftly to prevent the spread of infections. The primary cells involved in this response are phagocytes and natural killer (NK) cells.
Phagocytes
Phagocytes police the peripheral tissues by removing cellular debris and responding to the invasion of foreign substances or pathogens. Many phagocytes attack and remove microorganisms even before lymphocytes detect them. The human body has two general...
Phagocytes
Phagocytes police the peripheral tissues by removing cellular debris and responding to the invasion of foreign substances or pathogens. Many phagocytes attack and remove microorganisms even before lymphocytes detect them. The human body has two general...