Method Description

This flow cytometric assay quantitates the following CD4 and CD8 T-cell subsets: naive (global and CD62L+), memory (global, central, and effector memory), and activated (CD4+25+ and major histocompatibility [MHC] class II-positive) T cells. EDTA-anticoagulated blood is incubated with antibodies to various T-cell markers (ie, CD3, CD4, CD8, CD45RO, CD45RA, HLA-DR, CD27, CD62L, CD25, and CD28). After red blood cell lysis, the sample is washed to remove any unbound antibodies. Each T-cell subset is expressed as a percentage of total CD4+ or CD8 T cells. Only the CD3 T cells are expressed as a percentage of total lymphocytes. The absolute counts for the T-cell subsets are derived from flow cytometry analysis of whole blood using monoclonal antibodies to identify CD45, CD3, CD4, and CD8. The T-cell subsets panel is linked to the TCD4 test (TCD4 / CD4 Count for Immune Monitoring, Blood) within the experiment and, therefore, the CD3, CD4, and CD8 T-cell reference ranges are provided within the TCD4 assay. The results for the other T-cell subsets are interpreted using a reference range derived from data of normal healthy adult and pediatric donors. Isotype controls are used in each assay to measure background fluorescence of the samples. A normal, healthy control is also included in each experiment to ensure the optimal performance of the assay.(Unpublished Mayo information)