Apoptosis in interleukin-3-dependent haemopoietic cells. Quantification by two flow cytometric methods

Area of Science:

• Cell biology
• Immunology
• Biotechnology

Background:

• The murine BAF3 haemopoietic cell line undergoes apoptosis upon withdrawal of interleukin-3 (IL-3).
• Quantifying apoptosis is crucial for understanding cell death pathways and the effects of growth factors.
• Existing methods for apoptosis detection can be time-consuming or require specialized equipment.

Purpose of the Study:

• To describe and validate two novel flow cytometric methods for quantifying apoptotic cells.
• To assess the utility of these methods in studying the impact of cytokines on apoptosis.
• To provide efficient tools for apoptosis research in haemopoietic cell lines.

Main Methods:

• Method 1: Ethanol fixation, propidium iodide staining, and DNA histogram analysis to detect the 'sub-G1' peak characteristic of apoptotic cells.
• Method 2: Incubation with Hoechst 33342 dye, which is rapidly taken up by apoptotic cells, followed by propidium iodide addition for non-viable cell enumeration.
• Validation using cell sorting, DNA gel electrophoresis, light, and electron microscopy.

Main Results:

• Both flow cytometric methods successfully quantified apoptotic BAF3 cells following IL-3 withdrawal.
• The 'sub-G1' peak in DNA histograms reliably indicated apoptotic cells.
• Hoechst 33342 uptake correlated with apoptosis, and propidium iodide distinguished non-viable cells.

Conclusions:

• The described flow cytometric methods offer efficient and accurate means to quantify apoptosis in BAF3 cells.
• These techniques are valuable for investigating the role of cytokines in regulating cell survival and apoptosis.
• The methods provide a basis for further studies on apoptosis in haemopoietic cells.