APII223881222 - CME/CMLE - Flow Cytometry-APII223881222

APII223881222 - Educational Activity

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Flow cytometry is a powerful analytical technique that enables the identification and separation of different cell types based on their physical and chemical characteristics. The method involves passing cells in a fluid stream through a laser beam, measuring the scattered light to gather information about cell size (forward scatter, FSC) and internal complexity (side scatter, SSC). Fluorochrome-conjugated antibodies can also be used to label specific cell surface antigens, which emit fluorescence when excited by the laser, providing additional data for cell identification.<br /><br />The components of a flow cytometer include a fluidic system for cell alignment, a laser for excitation, and optical/electronic systems to collect, digitalize, and analyze light signals. Cells are aligned in a single file and passed through the laser beam, and the scattered and emitted light is detected and quantified. When fluorochromes are used, their emissions are separated and measured to identify specific cellular markers. <br /><br />Common CD markers used in clinical applications include CD3 and CD19 for identifying T and B lymphocytes, respectively, and CD4 and CD8 for distinguishing helper and cytotoxic T cells. The ratio of CD4:CD8 is clinically significant for assessing immune status, particularly in HIV/AIDS patients, where a lowered ratio indicates disease progression. CD45 is another broadly used marker that identifies leukocytes and is essential for differentiating between various blood cells. CD16 and CD56 are markers for natural killer (NK) cells and help distinguish among different immune cell types, with changes in CD56 expression linked to conditions like HIV infection.<br /><br />Flow cytometry's clinical applications extend beyond immunophenotyping to fields like infectious disease monitoring and cancer diagnostics. The technology continues to advance with the development of multicolor flow cytometry and a growing array of fluorochromes, enhancing its capability to distinguish closely related cell types and functional subgroups.

Keywords

Flow cytometry

Cell identification

Fluorochrome-conjugated antibodies

CD markers

Immune status

Laser excitation

Fluidic system

Clinical applications

Multicolor flow cytometry

HIV/AIDS