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Clinical and Diagnostic Laboratory Immunology, May 2000, p. 336-343, Vol. 7, No. 3
1071-412X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

Evaluation of TruCount Absolute-Count Tubes for Determining CD4 and CD8 Cell Numbers in Human Immunodeficiency Virus-Positive Adults

Carol T. Schnizlein-Bick,1,* John Spritzler,2 Cynthia L. Wilkening,2 Janet K. A. Nicholson,3 Maurice R. G. O'Gorman,4 Site Investigators,dagger and The NIAID DAIDS New Technologies Evaluation GroupDagger

Department of Medicine/Infectious Diseases, Indiana University School of Medicine, Indianapolis, Indiana 462021; Harvard School of Public Health, Boston, Massachusetts 021462; Division of HIV/AIDS, National Center for Infectious Diseases, Atlanta, Georgia 303333; and The Children's Memorial Hospital and Department of Pediatrics, Northwestern University Medical School, Chicago, Illinois 606144

Received 26 April 1999/Returned for modification 3 August 1999/Accepted 27 September 1999

A single-platform technology that uses an internal bead standard and three-color flow cytometry to determine CD4 and CD8 absolute counts was evaluated for reproducibility and agreement. Values obtained using TruCount absolute-count tubes were compared to those obtained using a two-color predicate methodology. Sixty specimens from human immunodeficiency virus type 1-infected donors were shipped to five laboratories. Each site also analyzed replicates of 14 human immunodeficiency virus type 1-infected local specimens at 6 h and again at 24 h. The interlaboratory variability was significantly less with TruCount (median difference in percent coefficient of variation [%CV] between the two methods was -8% and -3% for CD4 and CD8, respectively) than with the predicate method. Intralaboratory variability was smaller, with a median difference in %CV of -1% for both CD4 and CD8 with 6-h samples and -2% and -3% for CD4 and CD8, respectively, with 24-h samples. Use of TruCount for shipped samples resulted in a median CD4 count change of 7 cells (50th estimated percentile) when all laboratories and CD4 strata were combined. For on-site samples, the median CD4 count change was 10 CD4 cells for 6-h samples and 2 CD4 cells for 24-h samples. Individual site biases occurred in both directions and cancelled each other when the data were combined for all laboratories. Thus, the combined data showed a smaller change in median CD4 count than what may have occurred at an individual site. In summary, the use of TruCount decreased both the inter- and intralaboratory variability in determining absolute CD4 and CD8 counts.

* Corresponding author. Mailing address: Department of Medicine/Infectious Diseases, Indiana University School of Medicine, 1001 W. 10th St. Room OPW 430, Indianapolis, IN 46202-2879. Phone: (317) 630-6971. Fax: (317) 630-7522. E-mail: cschnizl{at}iupui.edu.

dagger S. Mudzinski, Albany Medical College; S. Peters, Georgetown University Hospital; S. Plaeger, University of California, Los Angeles, School of Medicine; C. Schnizlein-Bick, Indiana University School of Medicine; C. Spina, University of California, San Diego, School of Medicine; M. Waxdal and C. Monical, FAST Systems; J. Lowder and A. Shiba, BD Biosciences.

Dagger E. Bessent, University of California, San Diego; A. Donnenberg and S. Douglas, Children's Hospital of Philadelphia; F. Mandy, Bureau for HIV/AIDS and STD, LCDC, Health Canada; J. Nicholson, Centers for Disease Control and Prevention; M. O'Gorman, Northwestern University Medical School; S. Plaeger, University of California, Los Angeles; K. Reimann, J. Spritzler, and C. Wilkening, Harvard School of Public Health; J. Schmitz, University of North Carolina; C. Schnizlein-Bick, Indiana University; J. Kagan and D. Livnat, Division of AIDS, National Institute of Allergy and Infectious Diseases.

Clinical and Diagnostic Laboratory Immunology, May 2000, p. 336-343, Vol. 7, No. 3
1071-412X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.


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