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Test ID: TBBS    
T- and B-Cell Quantitation by Flow Cytometry

Method Description Describes how the test is performed and provides a method-specific reference

The T- and B-cell surface marker assay uses monoclonal antibodies to identify the various membrane antigens, and flow cytometry to enumerate the number of cells expressing these differentiation antigens. CD14 is used to exclude monocytes, thereby improving accuracy and enhancing the purity of the lymphocyte population. The results are reported as the percent of lymphocytes that are T cells (CD3+), T-helper (CD3+, CD4+), T-suppressor(CD3+,CD8+), natural killer (CD16+CD56+, CD3-), and B lymphocytes(CD19+), and the absolute number of each cell type per microliter of blood. The assay is a 7-color, no-wash procedure and the absolute counts are calculated from internal bead standards. The total CD45+ lymphocyte count (reported as thousand cells per microliter) and the CD4:CD8 ratio is also reported.(Hoffman RA, Kung PC, Hansen WP, Goedstien G: Simple and rapid measurement of human T lymphocytes and their subclasses in peripheral blood. Proc Natl Acad Sci USA 1980;77:4914-4917; US Department of Health and Human Services: Guidelines for performance of CD4+ T-cell determinations in persons with human immunodeficiency virus infection. MMWR 46 no. RR-2: 1997, pp 1-29)

Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.

Monday through Sunday

Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.

Same day/1 day

Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result

2 days

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

3 days

Performing Laboratory Location The location of the laboratory that performs the test

Rochester