Product Catalog

Labeled Annexin-V, with its high affinity for phosphatidylserine (PS), is a sensitive probe for PS exposed on the outer layer of apoptotic cells. Since necrotic cells also expose PS as a result of lost membrane integrity, propidium iodide is utilized as a DNA stain to distinguish necrotic cells from Annexin-V-labeled cell clusters. Other secondary labeling is possible, such as membrane-surface staining with phycoerythrin- or TRITC-labeled monoclonal antibodies for further cellular characterization.

Detection: Annexin-V-FLUOS can be directly detected in FACS analysis and immunochemistry without a secondary detection system.
Sample material: Cell lines and freshly isolated cells.
Specificity: Annexin-V-FLUOS binds in a Ca²⁺-dependent manner to negatively charged phospholipid surfaces, and shows high specificity for phosphatidylserine. Therefore, it stains apoptotic and necrotic cells. Propidium iodide stains only the DNA of leaky necrotic cells and allows for a distinction between apoptotic and necrotic cells.

In the early stages of apoptosis, changes occur at the cell surface. One of these plasma membrane alterations is the translocation of phosphatidylserine (PS) from the inner side of the plasma membrane to the outer layer, exposing PS at the surface of the cell. Macrophages specifically recognize PS exposed on the cell surface of lymphocytes during the development of apoptosis. The recognition and phagocytosis of apoptotic cells and bodies protects organisms from exposure to cellular compounds that lead to inflammation, which usually accompanies necrosis. Annexin V is a Ca²⁺-dependent phospholipid-binding protein with a high affinity for PS, making labeled annexin an excellent detection agent.

1. Annexin-V-FLUOS Solution, ready-to-use
2. Propidium iodide Solution, ready-to-use
3. Incubation Buffer (Hepes Buffer), ready-to-use

A typical FACS analysis is shown in Figure 1, after staining cells with labeled Annexin-V and propidium iodide.



Figure 1: Apoptotic and necrotic U937 cells identified in FACS analysis after staining with Annexin-V-FLUOS and Propidium iodide (PI). Cells were cultivated for 4 hours in the presence (lower row) or absence (upper row) of 4 μg/ml camptothecin (CAM).
A: Single-parameter Annexin-V-FLUOS
B: Single-parameter propidium iodide
C: Dual-parameter with Annexin-V-FLUOS (FL1) and propidium iodide (FL2)

Please go to the online technical support for regulatory and license disclaimers