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Lymphocyte Analysis (T-cell subsets, CD19, CD56) by FLOW*

Test Code


Test Synonyms

T-cell, B-cell and NK-cell enumeration


CD4, B cell and NK subsets


Flow cytometry, multiparameter analysis

* Performed by affiliate laboratory

Turnaround Time

3 days

Specimen Requirements

4 mL (min. 0.5mL) whole blood EDTA (Lavender), K EDTA (pink), or sodium or lithium heparin (green)

Specimen Stability
Specimen stable for 72 hours at room temperature
Storage & Handling

Ship ambient. Protect from extreme temperature with an ice pack. Separate ice pack from specimen.

Causes for Rejection

Clotted or hemolyzed specimens. Refrigerated: Unacceptable; Frozen: Unacceptable.

Reference Range

See report


This test is used to evaluate immunologic status using flow cytometry to quantify lymphocyte subsets. Clinicians order this test for primary immunodeficiencies, initial work up for HIV patients and in situations of immune dysfunction.  CD4 extended provides clinicians with a quantitative analysis of the following major lymphocyte subsets; T-cells, B-cells and NK-cells (natural killer). In addition to the reported parameters of CD4, percentages are reported for CD19+ B-cells and CD56+ natural killer cells.

  1. Maurice R. G. O’Gorman and Janet K. A. Nicholson. (2000). Adoption of single-platform technologies for enumeration of absolute T-lymphocyte subsets in peripheral blood. Clin Diagn Lab Immunol. 7(3):333–335.
  2. Orieji C. Illoh. (2004). Current applications of flow cytometry in the diagnosis of primary immunodeficiency diseases. Archives of Pathology and Laboratory Medicine. 128(1):23–31.