A simple method for quantifying high density antigens in erythrocyte membrane by flow cytometry.

Area of Science:

• Biomedical Engineering
• Cell Biology
• Analytical Chemistry

Background:

• Flow cytometry is standard for quantifying antigen content on red blood cells (RBCs).
• Current methods require saturating antibody concentrations, which can cause agglutination with high-density antigens, leading to inaccurate results.
• Agglutination inflates scattering and fluorescence signals, compromising data integrity.

Purpose of the Study:

• To apply the Langmuir adhesion model for accurate quantification of high-density antigens on RBCs.
• To overcome limitations of traditional flow cytometry methods that are susceptible to agglutination.
• To determine the antigen content of Glycophorin A (GPA) on RBC membranes.

Main Methods:

• Utilized flow cytometry to measure fluorescence intensity of RBCs at sub-saturating concentrations of anti-GPA antibodies.
• Applied the Langmuir adsorption model to analyze the relationship between antibody concentration and fluorescence.
• Focused analysis on the principal fluorescence peak corresponding to isolated cells when agglutinates were present.

Main Results:

• The Langmuir adsorption model successfully quantified Glycophorin A (GPA) antigen content on RBCs.
• GPA antigen content ranged from 3 to 13 x 10^5 sites per cell across nine samples, consistent with literature values.
• The model effectively accounted for variations and potential agglutination, ensuring reliable measurements.

Conclusions:

• The Langmuir adsorption model provides a robust method for determining antigen content on RBCs, particularly for high-density antigens.
• This approach mitigates errors caused by agglutination in flow cytometric analysis.
• The model shows potential for quantifying high-density antigens not only in RBCs but also in other cell types.