Flow Cytometry Separates Different Cell Types

Some cell types differ sufficiently in density that they can be separated on the basis of this physical property. White blood cells (leukocytes) and red blood cells (erythrocytes), for instance, have very different densities because erythrocytes have no nucleus; thus these cells can be separated by equilibrium density centrifugation (described shortly). Because most cell types cannot be differentiated so easily, other techniques such as flow cytometry must be used to separate them.

A flow cytometer identifies different cells by measuring the light that they scatter and the fluorescence that they emit as they flow through a laser beam; thus it can sort out cells of a particular type from a mixture. Indeed, a fluorescence-activated cell sorter (FACS), an instrument based on flow cy-tometry, can select one cell from thousands of other cells (Figure 5-34). For example, if an antibody specific to a certain cell-surface molecule is linked to a fluorescent dye, any

Filter

Filter

Fluorescent light detector

Fluorescent light detector

Laser beam

Cell suspension Sheath fluid

Drops with u00o<

lesser charge ^^^^cfo0 cf&o

Drops with no charge

Laser beam

Drops with u00o<

lesser charge ^^^^cfo0 cf&o

Cell suspension Sheath fluid

Scattered light detector

Scattered light detector

Drops with no charge

Fluorescent cells Nonfluorescent cell

Drops with greater charge

Fluorescent cell droplets Nonfluorescent cell droplet

Sorted charged droplets containing fluorescent cells

Was this article helpful?

0 0
Your Heart and Nutrition

Your Heart and Nutrition

Prevention is better than a cure. Learn how to cherish your heart by taking the necessary means to keep it pumping healthily and steadily through your life.

Get My Free Ebook


Post a comment