Flow cytometry

• In flow cytometry, cells marked with fluorescent antibodies flow one after another in a thin capillary through a laser light scattered by the respective cell. Based on this light scattering, both granularity and volume of the cells are measured and these signals are displayed on the monitor in an x-y diagram. In this way, cells of the same group can be electronically sorted out of a cell mixture and identified.
• By means of specific, monoclonal, fluorescence-coupled antibodies (mAk), surface molecules (see CD classification below) of the cells can be determined and thus certain properties and functions of the cells can be defined (see also basophil activation test).
• The measuring device consists of a combined system of optics and electronics. The fluorescent dyes coupled to the mAk`s are first excited by a laser. The emitted fluorescence signals are then received by photon amplifiers and finally transmitted as an event to a computer where they can be processed. Depending on the specification of the equipment used, three or more different fluorescent dyes can be used simultaneously in one analysis. Excited by laser light, they then emit easily separable light signals that can be analyzed separately with detectors.

Application e.g. for:

• Characterization of cutaneous lymphomas
• Cell activation detection
• HIV infection (diagnostics and course of therapy)
• Apoptosis detection (influence of drugs, e.g. after high-dose steroid therapy, after UVA or UVB irradiation)
• Intracellular cytokine detection (characterization of Th1/TH2 cells)
• Cell cycle analyses of cell populations (determination of Go/G1/G2/ M/S phase)
• Phagocytosis measurements (monocytes and granulocytes)
• Measurements of the respiratory burst (monocytes and granulocytes)
• Basophil activation test (e.g. for suspected wasp venom allergy; for latex allergy see basophil degranulation test below)
• Sperm analysis.