This article is a US government work and, as such, is in the public domain in the United States of America.
Toward quantitative fluorescence measurements with multicolor flow cytometry†
Article first published online: 28 DEC 2007
Published 2007 Wiley-Liss, Inc.
Cytometry Part A
Special Issue: Cytometry in the Age of Systems Biology—Proceedings Papers from the XXIV International Congress of the International Society for Analytical Cytology
Volume 73A, Issue 4, pages 279–288, April 2008
How to Cite
Wang, L., Gaigalas, A. K., Marti, G., Abbasi, F. and Hoffman, R. A. (2008), Toward quantitative fluorescence measurements with multicolor flow cytometry. Cytometry, 73A: 279–288. doi: 10.1002/cyto.a.20507
- Issue published online: 20 MAR 2008
- Article first published online: 28 DEC 2007
- Manuscript Accepted: 12 NOV 2007
- Manuscript Received: 6 SEP 2007
- multicolor cytometry;
- biological standard
A procedure is presented for calibrating the output of a multicolor flow cytometer in units of antibodies bound per cell (ABC). The procedure involves two steps. First, each of the fluorescence channels of the flow cytometer is calibrated using Ultra Rainbow beads with assigned values of equivalent number of reference fluorophores (ERF). The objective of this step is to establish a linear relation between the fluorescence signal in a given fluorescence channel of multicolor flow cytometers and the value of ERF. The second step involves a biological standard such as a lymphocyte with a known number of antibody binding sites (e.g., CD4 binding sites). The biological standard is incubated with antibodies labeled with one type of fluorophores for a particular fluorescence channel and serves to translate the ERF scale to an ABC scale. A significant part of the two-step calibration procedure involves the assignment of ERF values to the different populations of Ultra Rainbow beads. The assignment of ERF values quantifies the relative amount of embedded fluorophore mixture in each bead population. It is crucial to insure that the fluorescence signal in a given range of fluorescence emission wavelengths is related linearly to the assigned values of ERF. The biological standard has to posses a known number of binding sites for a given antibody. In addition, this antibody has to be amenable to labeling with different types of fluorophores associated with various fluorescence channels. The present work suggests that all of the requirements for a successful calibration of a multicolor flow cytometer in terms of ABC values can be fulfilled. The calibration procedure is based on firm scientific foundations so that it is easy to envision future improvements in accuracy and ease of implementation. Published 2007 Wiley-Liss, Inc.