Copyright 1995, The University of Texas Medical School at Houston
Laboratory Test Guide

CD4-CD8 Lymphocyte Profile

Synonyms: CD4-CD8; T and B lymphocyte profile; T-cell subset

Hermann Test Code: 8180020

CPT Code(s): 88180 (x5)

Specimen Requirement: Avoid clots and hemolysis. Include collection time on requisition.

Container: 5 ml EDTA (purple top) tube or 10ml ACD tube(please send WBC and differential results).

Transport: In biohazard bag at room temperature (avoid temperature extremes). Deliver within 24 hours.

Patient Preparation: None

Test Availability:

• Sunday 12:00 p.m. to Friday at 4:30 p.m

• Report available within 24 hours

Methodology: Flow cytometric quantitation of fluorescent-tagged monoclonal antibodies directed against lineage specific cell surface proteins.

Clinical Utilization:

• Monitoring HIV infected pediatric and adult patients recommended every 3-6 months

• Establishing diagnosis for primary/secondary immunodeficiency

Reference Range(s): Established on peripheral blood.

• CD3 64-89%

• CD4 33-59%

• CD8 22-53%

• CD19 4-2099%

• CD16+56 2-23%

• CD4/CD8 Ratio: 0.70-2.60

Interpretation:

T-cell subset analysis is performed by flow cytometry. Flow cytometry is the quantitative multiparameter measurement of chemical or physical characteristics of cells in suspension. A flow cytometer measures as a cell passes through detectors:

1) the cell's light scatter; and

2) the electronic cell volume.

It also measures as it passes through a fluorescent excitation beam the cell's:

3) axial (at a right angle) light loss; and

4) morphological information (derived from the cell shape or time duration of light scatter signals.

By incubating cells with fluorescent-tagged antibodies directed against lineage specific cell surface antigens, the composition of antigens on the cell surface is determined (phenotype). The perfomance of the T-cell subset analysis follows the strict guidelines to account for all lymphocytes and for quality assurance issued by the CDC using the following antibodies, isotype control, CD45, CD14, CD3, CD4, CD8, CD19, CD16, and CD56 in combination.

Monitoring HIV Infected Individuals. Enumeration of the percent and absolute cell counts of CD4 (helper) and CD8 (suppressor) T-cells is relevant in HIV infection. The CD4 positive cell count provides a direct indicator of disease progression in adult and pediatric AIDS patients. The three CD4-positive lymphocyte categories are:

Category 1: >500 CD4+ cells/cumm
Category 2: 200-499 CD4+ cells/cumm
Category 3: <200 CD4+ cells/cumm

The Public Health Service has recommended monitoring CD4/CD8 counts every 3-6 months to closely follow these patients.

Immunodeficiency. Primary immunodeficiencies can be detected by characterization of the lymphocyte subpopulation changes. Bruton -Type X-Linked Infantile Agammaglobulinemia is a primary B-cell defect and is characterized by absent B-cells. Severe Combined Immunodeficiency Disorders (SCID) affects both B- and T-cells and has decreased T- and B-cells. DiGeorge Syndrome is a primary T-cell defect and will have decreased T-cells and increased B-cells. Ataxia Telangiectasia has both T- and B-cells affected and will demonstarte decreased T-cells and increased B-cells. Wiskott-Aldrich Syndrome is a primary B- and T-cell defect with decreased T-cells and decreased to increased B-cells.

Literature:

• Taylor J.M.G., Fahey J.L., Detels R., Giorgi J.V. CD4 percentage, CD4 number, and CD4:CD8 ratio in HIV infection. J AIDS 1989; 2:114-124.

• Giorgi J.V., Detels R.. T-cell subset alterations in HIV-infected homosexual men: NIAID multicenter AIDS cohort study. Clin Immunol 1989; 52:10-18.

• Nicholson J.K.A.Use of flow cytometry in the evaluation and diagnosis of primary and secondary immunodeficiency disease. Arch Pathol Lab Med 1989;113:598-605.

• CDC Morbidity and Mortality Report. May 8, 1992.

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Author(s): Anne LeMaistre, M.D.
Released: 11/94 -- Last Reviewed: 11/94