Standardization of absolute CD4+ lymphocyte counts across laboratories: an evaluation of the Ortho CytoronAbsolute flow cytometry system on normal donors.

Important note: Information in this article was accurate in 1996. The state of the art may have changed since the publication date.

Standardization of absolute CD4+ lymphocyte counts across laboratories: an evaluation of the Ortho CytoronAbsolute flow cytometry system on normal donors.

Cytometry. 1995 Sep 15;22(3):200-10. Unique Identifier : AIDSLINE MED/96106603
Connelly MC; Knight M; Giorgi JV; Kagan J; Landay AL; Parker JW; Page E; Spino C; Wilkening C; Mercolino TJ; Immunocytometry Research and Development, Ortho Diagnostic; Systems, Raritan, New Jersey 08869, USA.

Abstract: The Ortho CytoronAbsolute is a flow cytometer designed to provide direct absolute counts of lymphocytes and their subsets from a single instrument. This study was designed to determine the performance of four geographically separated CytoronAbsolute instruments using 24-h-old, shipped, whole blood samples and to compare the results obtained on the CytoronAbsolute to those obtained using combinations of hematology instruments and other flow cytometers. The absolute count feature of the CytoronAbsolutes located at the four sites were cross calibrated and gave across-site coefficients of variation (CVs) of <4.0% for absolute count and 8.2% for absolute lymphocyte count. The calibration was stable for at least 2 months. Absolute lymphocyte counts and lymphocyte percentage immunophenotypes were determined on blood from 50 healthy human immunodeficiency virus (HIV)-seronegative donors. There were no significant site-to-site differences (each P > .05) in CD3+/CD4+ absolute lymphocyte counts determined on the CytoronAbsolute. In contrast, there was a significant site-to-site difference (P < .001) between sites 2 and 3 and sites 3 and 4 in the absolute CD3+/CD4+ lymphocyte counts determined via the conventional method of combining a flow cytometry-derived percentage with a hematology instrument-derived lymphocyte count. There was no significant difference (P = .388) in CD3+/CD4+ lymphocyte percent determinations between the CytoronAbsolute and the FACScan or Profile II flow cytometers used in this study. These results demonstrate that different operators can cross calibrate CytoronAbsolutes for absolute CD3+/CD4+ lymphocyte subset determinations, even over large geographic distances.

Keywords: Calibration CD4 Lymphocyte Count/*METHODS Evaluation Studies Flow Cytometry/*INSTRUMENTATION Human Reproducibility of Results Tissue Donors JOURNAL ARTICLE
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