Latest in Haematology analysers 

Fluorescence Flow Cytometry

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Haematology has evolved into an interesting subject due to the advanced technology. Also, over the past few years, the market penetration of Haematology analysers has increased significantly in laboratories across the country. 

The latest technology in haematology analysers is Fluorescence Flow Cytometry (FCM) the term "cytometry" is defined as a measurement of physicochemical properties of cells and other biological particles. Flow cytometry offers measurements of cells and other particles flowing in thin streams. Generally, it detects optical information from cells or other particles flowing in a thin stream under irradiation of a laser beam. Such optical information sources include scattered light and fluorescence depending on the measurement objective.

Since the late 1990s, cell counter manufacturers have been looking at flow cytometry techniques as a way of increasing the capabilities of cell counters as traditional flow cytometry instrumentation requires the use of highly specific antigen-antibody reactions; requiring pre-incubation and use of expensive reagents. In addition, gating of cell scattergram is complex which is manually performed by skilled operator, complexities of the reagents used, requirements of manual pipetting and not all applications are automated.

Haematology analysers with FCM use florescence dye to stain all sampled cells, increasing specificity and extension of clinical applications beyond the realm of traditional cell counting, without the complexity and cost of antigen/antibody reactions.

Recently,ingenious Fluorescence Flow Cytometry (FCM) Technology platform is introduced in mid-size haematology analysers, which was successfully introduced with top-of-the-end haematology analysers. These analysers with FCM offer excellent capabilities of best differentiation of normal cells and pathological cells; and interference is managed better than before and that also without compromising throughput and reliability.

The major benefit of FCM to its users is improved detection of pathological cells like Immature Granulocyte Count, High Fluorescence Lymphocyte Count, Abnormal Lymphocyte Detection. The other advantage is improved quality of five part differential of WBC with 48-72 hours stability after blood collection and that also for High linear ranges (no dilution necessary). It has a stable and long life detector system requiring no calibration.

As depicted in the image of Optical System of haematology analysers with FCM, it detects each cell from three angles:

•  Forward Scattered Light (Information on Cell Volume).
• Side Scattered Light (Information on Internal Cell structure).
•  Side Fluorescence Light (Information on RNA/DNA content).

Fluorescence Light detects DNA/RNA information of cells along with information about Cell activity such as:

•  Duplication activity of the nucleus (High RNA).
•  Cytoplasm activity (Protein synthesis).

This information is useful for very good differentiation of mature and immature cells. With the use of artificial intelligence based complex computer algorithm, this differentiation is plotted as easy to interpret scattergram by the haematology analysers.

Hence, FCM enables haematology analysers to differentiate not only mature WBCs, but also mature and immature WBCs. By staining the cells, analytical sensitivity of cell counter is enhanced and signal-to-noise ratio is increased. Reportable ranges are extended and interferences are reduced. FCM enables Haematology analysers are now able give more detailed IP messages and suspect messages like Neutropenia, Neutrophilia, Lymphopenia, Lymphocytosis, Monocytosis, Eosinophilia, Basophilia, Leukocytopenia, Leukocytosis, NRBC Present, Blasts?, Immature Gran?, Left Shift?, Abn Lympho/L_Blasts?, lymphocytes, NRBC?, RBC Lyse Resistance?, Atypical Lympho?, Anisocytosis, Microcytosis, Macrocytosis, Hypochromia, Anemia, Erythrocytosis and Reticulocytosis.

They are also able to analyse special parameters like Florescence Platelet (PLT-FL), immature Granulocytes (IG), Nucleated Red Blood Cell (NRBC), Hematopoietic Progenitor Cells (HPC), Reticulocyte, Immature Reticulocyte Fraction (IRF), Reticulocyte Hemoglobin (RET-He), Immature Platelet Fraction (IPF). Analysis of these parameters give insight in to bone marrow erythropoietic activity, timing for apheresis in peripheral blood stem cell transplantation, clinical information of peripheral platelet destruction and marrow failure in thrombocytopenic patients.

Sri Lanka Society for Medical Laboratory Science

kumudeshr@gmail.com / 0094773077717