Flow cytometry: a tool in immunohematology for D+W (Du) antigen evaluation?

Area of Science:

• Transfusion Medicine
• Immunology
• Hematology

Background:

• The D antigen is a critical determinant in Rh blood group system compatibility.
• D+W (previously Du) represents a variant D antigen expression, posing challenges in serological testing.
• Accurate D antigen phenotyping is essential for preventing alloimmunization and hemolytic disease of the fetus and newborn.

Purpose of the Study:

• To quantify and compare D antigen expression levels in D+W samples versus standard D-positive and D-negative red blood cells.
• To establish flow cytometry as a method for grading D antigen expression.
• To evaluate the utility of flow cytometry for resolving cases of weak D antigen expression that are difficult to assess by traditional agglutination methods.

Main Methods:

• Flow cytometry was utilized to analyze D antigen expression on red blood cells.
• Immunofluorescence and Mean Channel Value (MCV) of fluorescence quantified antigen intensity.
• D+W, D-positive (cde phenotype), and D-negative control samples were analyzed.

Main Results:

• D+W samples demonstrated significantly lower D antigen expression (p > 0.001) compared to D-positive samples.
• D-negative (cde) samples showed minimal to no D antigen expression, similar to negative controls.
• Flow cytometry allowed for the grading of D antigen expression intensity.

Conclusions:

• Flow cytometry offers a sensitive and quantitative method for assessing D antigen expression.
• This technique can differentiate D+W variants from true D-positive and D-negative red blood cells.
• Grading D antigen expression via flow cytometry enhances the ability to manage complex RhD typing cases.