Quick Review Cards for Medical Laboratory Science

Flow Cytometry Hematology Review 337

Principle

Measurements

Applications

Measurement of physical, antigenic, functional properties of cells suspended in fluid

Fluorescence: Cells stained with antibodies conjugated to specific fluorochrome pass 1 by 1 in front of laser light

source. Electrons of fluorochrome raised to higher energy state; emit light of specific wavelength as they return

to ground state. Emitted light detected by photodetectors for specific wavelengths.

Forward scatter (FS): Photodetector in line with laser beam measures forward scatter (FS). Proportional to

volume or size.

Side scatter (SS): Photodetector to side measures side scatter (SS). Reflects surface complexity & internal structures.

FS, SS, fluorescence displayed simultaneously on screen. Cell populations with similar characteristics form clusters

on dot plot. Specific populations can be selected with cursor (gating).

Immunophenotyping: Differentiating cells on basis of surface & cytoplasmic markers. Can determine lineage &

maturity of cells in hematologic malignancies. Useful for Dx, follow-up, & prognosis. Certain immunopheno-

types associated with specific cytogenetic abnormalities.

Dx & monitoring of immunodeficiencies

Dx of paroxysmal nocturnal hemoglobinuria

Enumeration of stem cells

Quantitation of fetal hemoglobin