INTRODUCTION TO FLOW CYTOMETRY - Flow Cytometry in Drug Discovery and Development - page 7

FIGURE 1.3 An example of fluorescence emission of various wavelengths (top) as it passes
through different types of optical filters (bottom).

TABLE 1.2 Partial List of Filters Typically Employed with
Various Fluorochromes

Fluorochrome Filter

Pacific Blue, BD Horizon V450, CasB 440/40

AmCyan 525/40

FITC, AlexaFluor 488 (AF488) 530/30

CasY, AF430 545/90

PE 585/40

PE-Texas Red, AF595 625/40

APC, AF647 660/20

PE-Cy5, PerCP-Cy5.5, PerCP 695/40

APC-Cy5.5 705/50

AF700 720/45

PE-Cy7, BD-APC H7 780/60

1.5 TYPES AND CHOICE OF FLUOROCHROMES

Afluorochrome is a fluorescent marker that emits a particular wavelengthwhen a laser
light hits it. Fluorescence occurs when a molecule, which is excited by light from a
laser at one wavelength, loses its energy and emits light of a longer wavelength. The
emitted wavelength is what is detected. The excited and emitted light are of different
wavelengths. The fluorescence intensity that is emitted is proportional to the quantity
of binding sites for the fluorescent compound on the cell. Therefore, the more the
fluorescence that is emitted the more the binding sites on the cell. For instance, for an
antibody tagged with FITC (fluorescein isothiocyanate, which is excited by a 488 nm