Flow Cytometry: Principles and Applications

288 Pages·2007·3.567 MB·English

by  Marion G. Macey BSc, PhD, FRCPath (auth.), Marion G. Macey PhD (eds.)

Flow Cytometry
Flow Cytometry
Principles and Applications
Edited by
Marion G. Macey,
PhD
Department of Haematology
The Royal London Hospital
London, United Kingdom
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Cover design by Nancy K. Fallatt
Cover illustration:(from left) typical lens and mirror assembly for detection of 90° LS, FITC, PE, and ECD
fluorescence (above; Fig. 8, Chap. 1, see full caption on p. 8); flow cytometric enumeration of cells that have
migrated through wells containing HUVECs (below; Fig. 3, Chap. 10, see complete figure and caption on
p. 230); fluorescence emission spectra for FITC and PE (Fig. 6, Chap. 1, see complete caption on p. 12);
chemical structure of a probe for estimating intracellular oxidants (Fig. 10B, Chap. 3, see complete figure
and caption on pp. 90–91); the light-scattering properties of platelets in diluted whole blood (Fig. 6, Chap.
10,see discussion on p. 244).
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eISBN 10-digit: 1-59745-451-6
eISBN 13-digit: 978-1-59745-451-3
Library of Congress Cataloging-in-Publication Data
Flow cytometry : principles and applications / edited by Marion G. Macey.
p. ; cm.
Includes bibliographical references and index.
ISBN 10-digit: 1-58829-691-7 (alk. paper)
ISBN 13-digit: 978-1-58829-691-7 (alk. paper)
1. Flow cytometry. 2. Cell separation. 3. Cytodiagnosis. I. Macey, Marion G.
[DNLM: 1. Flow Cytometry--methods. 2. Cell Separation--methods. 3. Cyto-
diagnosis--methods. QY 95 F644 2007]
QH585.5.F56F586 2007
616.07'582--dc22
2006039667
Preface
Improvements in instrument design and computing power and the increased
availability of fluorescent agents have led to an increased usage of flow cytometry
in both the research and clinical settings. Flow Cytometry: Principles and
Applications provides a comprehensive introduction to data interpretation, quality
control procedures, pitfalls and problems, in addition to detailed protocols from
leading authorities with extensive practical experience in flow cytometry. Flow
Cytometry: Principles and Applications also presents the principles and potential
of flow cytometry to assess many functional aspects of cells.
This is an essential handbook and reference to both new and experienced flow
cytometry users.
Marion G. Macey, PhD
Consultant Clinical Scientist
Professor of Immunohaematology
Department of Haematology
The Royal London Hospital
London, United Kingdom
v
Contents
Preface ..............................................................................................................v
Contributors .....................................................................................................ix
1 Principles of Flow Cytometry
Marion G. Macey..................................................................................1
2 Cell Preparation
Desmond A. McCarthy.......................................................................17
3 Fluorochromes and Fluorescence
Desmond A. McCarthy.......................................................................59
4 Quality Control in Flow Cytometry
David Barnett and John T. Reilly......................................................113
5 Experimental Design, Data Analysis, and Fluorescence Quantitation
Mark W. Lowdell..............................................................................133
6 Apoptosis Detection by Flow Cytometry
Paul Allen and Derek Davies............................................................147
7 DNA Analysis by Flow Cytometry
Derek Davies and Paul Allen............................................................165
8 Immunological Studies of Human Cells
Ulrika Johansson...............................................................................181
9 Calcium: Cytoplasmic, Mitochondrial, Endoplasmic Reticulum,
and Flux Measurements
Gary Warnes and Marion G. Macey.................................................209
10 Further Functional Studies
Marion G. Macey..............................................................................219
11 Cell Sorting by Flow Cytometry
Derek Davies.....................................................................................257
Appendix: Useful Internet Sites and Suppliers.............................................277
Index ............................................................................................................287
vii
Contributors
PAUL ALLEN, BSc, PhD • Centre for Haematology, Institute of Cell and
Molecular Sciences, Barts and The London School of Medicine
and Dentistry, London, United Kingdom
DAVID BARNETT, PhD, MRCPath • UKNEQAS, Sheffield, United Kingdom
DEREK DAVIES, BSc• FACS Laboratory, London Research Institute,
Cancer Research UK, London, United Kingdom
ULRIKA JOHANSSON, BSc, PhD • Department of Haematology, The Institute
of Cell and Molecular Science, Queen Mary University London, London,
United Kingdom
MARK W. LOWDELL, MSc, PhD, FRCPath• Senior Lecturer in Haematology,
Director of Laboratory of Cellular Therapeutics, The Royal Free and
UCL Medical School, London, United Kingdom
MARION G. MACEY, BSc, PhD, FRCPath • Professor, Department of Haematology,
The Royal London Hospital, London, United Kingdom
DESMOND MCCARTHY, BSc, PhD • School of Biological Sciences, Queen Mary
University London, London, United Kingdom
JOHN T. REILLY, MD, FRCPath • Professor, UKNEQAS, Sheffield, United
Kingdom
GARY WARNES,BSc, PhD • Imaging and Flow Cytometry Facility, The Institute
of Cell and Molecular Sciences, Queen Mary University London, London,
United Kingdom
ix
1
Principles of Flow Cytometry
Marion G. Macey
Summary
Flow cytometry is a powerful tool for interrogating the phenotype and characteristics
of cells. It is based upon the light-scattering properties of the cells being analyzed and
these include fluorescence emissions. This fluorescence may be associated with dyes or
conjugated to mAbs specific for molecules either on the surface or in the intracellular com-
ponents of the cell. Flow cytometry facilitates the identification of different cell types
within a heterogeneous population. It was initially developed by immunologists wishing to
separate out different cell populations for subsequent coculture experiments to determine
the function of cells within the immune system. This was achieved by using fluorescence-
activated cell sorting,or FACS,on the flow cytometer. The initial instruments were able to
analyze one or two colors of fluorescence; today,instruments capable of analyzing 11 colors
of fluorescence are available.
Key Words:Acquisition; amplification; fluorescence; histograms; light scatter.
1. History and Development of Flow Cytometry
Flow cytometry has developed over the last 60 yr from single-parameter
instruments that detected only the size of cells to highly sophisticated machines
capable of detecting 13 parameters simultaneously. A brief overview of the
development of flow cytometry is given in Table 1.
2. Principles of Flow Cytometry
All forms of cytometry depend on the basic laws of physics,including those
of fluidics,optics,and electronics (8). Flow cytometry is a system for sensing cells
or particles as they move in a liquid stream through a laser (light amplification
by stimulated emission of radiation)/light beam past a sensing area. The relative
light-scattering and color-discriminated fluorescence of the microscopic particles
is measured. Analysis and differentiation of the cells is based on size,granularity,
From: Flow Cytometry: Principles and Applications
Edited by: M. G. Macey © Humana Press Inc., Totowa, NJ
1
2 Macey
Table 1
A Brief History of Flow Cytometry
Year Development
1954 An instrument in which an electronic measurement for cell counting and
sizing was made on cells flowing in a conductive liquid with one cell at
a time passing a measuring point was first described by Wallace Coulter
(1). This became the basis of the first viable flow analyzer.
1965 Kamentsky et al. (2)described a two-parameter flow cytometer that measured
absorption and back-scattered illumination of unstained cells, and this
was used to determine cell nucleic acid content and size. This instrument
represented the first multiparameter flow cytometer, and the first cell
sorter was described that same year by Fulwyler (3). Use of an electrostatic
deflection ink-jet recording technique (Sweet) (4) enabled the instrument
to sort cells in volume at a rate of 1000 cells/s.
1967 Thompson (5)developed a system for the electrostatic charging of droplets
which enhanced the development of cell sorters. Van Dilla et al. (6)
exploited the real volume differences of cells to prepare suspensions of
highly purified (>95%) human granulocytes and lymphocytes.
1983 First clinical flow cytometers were introduced.
1990 Advances in technology, including availability of mAbs and powerful but
cheap computers, brought flow cytometry into routine use. Benchtop
instruments developed with enclosed flow cells were developed.
1995 The ability to measure a minimum of five parameters on 25,000 cells in 1 s
used routinely to enhance the diagnosis and management of various
diseasestates and understanding of the pathogenesis of disease.
1999 Instruments equipped with lasers and capable of analyzing 11 fluorochromes
developed by Bigos et al. (7).
2003 High-speed sorters using digital technology introduced.
and whether the cell is carrying fluorescent molecules in the form of either
antibodies or dyes. As the cell passes through the laser beam,light is scattered
in all directions, and the light scattered in the forward direction at low angles
(0.5–10°) from the axis is proportional to the square of the radius of a sphere
(9) and so to the size of the cell or particle. Light may enter the cell and be
reflected and refracted by the nucleus and other contents of the cell; thus, the
90° light (right-angled, side) scatter may be considered proportional to the
granularity of the cell. The cells may be labeled with fluorochrome-linked
antibodies or stained with fluorescent membrane, cytoplasmic, or nuclear
dyes. Thus, differentiation of cell types, the presence of membrane receptors
and antigens,membrane potential,pH,enzyme activity,and DNA content may
be facilitated.
Introduction to Flow Cytometry 3
Flow cytometers are multiparameter,recording several measurements on each
cell; therefore, it is possible to identify a homogeneous subpopulation within a
heterogeneous population. This is one of the most useful features of flow cytome-
ters and makes them preferable to other instruments such as spectrofluorimeters,
in which measurements are based on analysis of the entire population.
Most commercial flow cytometers have the capacity to make five or more
simultaneous measurements on every cell,but some specialized research instru-
ments have considerably greater capacity,and with three lasers it is possible to
analyze up to 11 parameters (7). A typical flow cytometer consists of three
functional units: (1) one or more laser light sources and a sensing system that
comprises the sample/flow chamber and optical assembly,(2) a hydraulic system
that controls the passage of cells through the sensing system,and (3) a computer
system that collects data and performs analytical routines on the electrical signals
relayed from the sensing system (Fig. 1).
The flow chamber is instrumental in delivering the cells in suspension to the
specific point that is intersected by the illuminating beam and the plane of focus
of the optical assembly. Flow chambers may comprise flat-sided cuvets to mini-
mize unwanted light reflections, and, where cell sorting is required, so-called
stream or “jet in air” flow cells are used.
Cells suspended in isotonic fluid are transported through the sensing system.
Most instruments use a lamina/sheath flow technique (10)to confine cells to the
center of the flow stream; this also reduces blockage due to clumping. Cells enter
the chamber under pressure through a small aperture that is surrounded by sheath
fluid. The sheath fluid in the sample chamber creates a hydrodynamic focusing
effect and draws the sample fluid into a stream. Accurate and precise positioning
of the sample fluid within the sheath fluid is critical to efficientoperation of the
flow cytometer, and adjustment of the relative sheath and sample pressures
ensures that cells pass one by one through the detection point. This alignment
may be performed manually on some machines, but in most it is fixed.
Water-cooled laser sources with an output power in the range of 50 mW–
5 W may be used for fluorescence and light-scatter measurements. Air-cooled
lasers have a maximum output of 100 mW and are now more commonly used
together with laser diodes in commercial instruments. Lasers have the advan-
tage of producing an intense beam of monochromatic light which in some
systems may be tuned to several different wavelengths. The most common
lasers used in flow cytometry are argon lasers, which produce light between
wavelengths of 351 and 528 nm. Other lasers used include UV lasers, which
produce light between 325 and 363 nm; krypton lasers, which produce light
between 350 and 799 nm; helium–neon lasers, which produce light at 543,
594, 611, and 633 nm; and helium–cadmium lasers, which produce light at
325 and 441 nm.
4 Macey
Fig. 1.Schematic representation of a flow cytometer,including the flow cell,sheath
stream,laser beam,sensing system computer,deflection plates,and droplet collection.
3. Fluorescence Analysis
Fluorescence is excited as cells traverse the laser excitation beam, and this
fluorescence is collected by optics at right angles to the incident beam. A barrier
filter blocks laser excitation illumination,while dichroic mirrors and appropriate
filters (see Section 4.1.) are used to select the required wavelengths of fluores-
cence for measurement. The photons of light falling upon the detectors are con-
verted by photomultiplier tubes (PMTs) to an electrical impulse,and this signal
is processed by an analog-to-digital (A-to-D) converter that changes the electri-
cal pulse to a numerical signal. The quantity and intensity of the fluorescence
are recorded by the computer system and displayed on a visual display unit as
a frequency distribution that may be single-parameter (Fig. 2), dual-parameter
(Fig. 3), or multiparameter. Single-parameter histograms usually convey infor-
mation regarding the intensity of fluorescence and number of cells of a given
fluorescence,so that weakly fluorescent cells are distinguished from those that
are strongly fluorescent.