Flow cytometric immunofluorescence and DNA analysis: using a 1.5 mW helium-neon laser (544 nm)

Area of Science:

• Flow Cytometry
• Laser Technology
• Cellular Analysis

Background:

• Traditional flow cytometry often relies on higher-power lasers like Argon lasers for immunofluorescence and DNA analysis.
• Evaluating alternative, lower-power lasers is crucial for cost-effectiveness and accessibility in research laboratories.
• The 544 nm HeNe laser presents a potential alternative due to its wavelength and lower power requirements.

Purpose of the Study:

• To assess the efficacy of a 1.5 mW HeNe laser (544 nm) for immunofluorescence and DNA analysis using an EPICS Elite flow cytometer.
• To compare the performance of the HeNe laser with a standard Argon laser for various cell conjugates and DNA staining.
• To determine the suitability of the HeNe laser for routine research applications in flow cytometry.

Main Methods:

• Utilized a 1.5 mW HeNe laser (544 nm) on an EPICS Elite flow cytometer with a 76-micron Sortsense flow cell.
• Performed immunofluorescence analysis using phycoerythrin (PE)-conjugated antibodies (CD4PE, CD56PE, CD19PE) and tandem dyes (ECD, Cy-Chrome).
• Conducted DNA analysis using Propidium Iodide (PI) staining for whole blood samples.

Main Results:

• Achieved a fluorescence threshold of approximately 336 MESF for PE calibration beads.
• Demonstrated high correlation coefficients (0.92-0.99) between HeNe and Argon laser analyses for various antibody conjugates.
• Obtained good separation of cell populations and low coefficient of variation (CV) of 2.6% for whole blood DNA fluorescence.

Conclusions:

• The 1.5 mW HeNe laser (544 nm) is sufficient for reliable immunophenotyping and DNA analysis on the EPICS Elite.
• The laser's performance is comparable to a 15 mW Argon laser, offering advantages in cost, size, and power consumption.
• Optimal excitation overlap and favorable water Raman scattering properties contribute to the HeNe laser's effectiveness.