Test Center

My Recent Searches

  • No Recent Search.

My Tests Viewed

  • No Test Viewed.

Lymphocyte Subset Panels

Lymphocyte Subset Panels

Test Highlight

Lymphocyte Subset Panels

  

Clinical Use

  • Determine immune status of patients with HIV infection

  • Monitor anti-retroviral and immunosuppressive therapy

  • Differential diagnosis of congenital and acquired immune deficiencies  

Clinical Background

The cellular and humoral immune systems are mediated by distinct lymphocyte classes or subsets including T-cells, B-cells, and natural killer (NK) cells. T-cells are involved in combating intracellular infections, cancer cells, and foreign tissue. B-cells give rise to the humoral immune system that is targeted against bacterial and viral infections. NK cells play a role in defense against viral infections and tumors. These lymphocyte subsets can be discerned by the antigenic properties of cell surface (membrane) markers. For example, T-cells are CD3 positive, B-cells are CD19 positive, and NK cells are CD3 negative and CD16 and CD56 positive. T-cells are further classified as helper cells (CD4 positive, CD4+) or cytotoxic cells (CD8 positive, CD8+). In turn, CD4+ and CD8+ cells can be classified as naïve (CD4RA+, CD8RA+) or memory cells (CD4RO+, CD8RO+).

Although there are a relatively fixed number and proportion of these lymphocyte subsets in normal individuals, the absolute number and proportion are altered in various diseases. For example, in individuals with human immunodeficiency virus (HIV) infection, the number of CD4+ cells and the proportion of CD4+ cells relative to CD8+ cells vary based on the stage of disease and therapeutic response. Thus, lymphocyte subset analysis can provide information regarding the immune status of the patient and assist in monitoring therapy. Lymphocyte subset analysis can also identify isolated T, B, or NK cell deficiency; confirm T cell deficiency indicated by a neonatal screen for T cell receptor excision circles (TRECs); and help classify severe combined immunodeficiency disease (SCID), which in turn helps predict infection risk and evaluate recurrent infections.

Method

In this 4-color multiparametric flow cytometry method, whole blood is first incubated with fluorochrome-conjugated monoclonal antibodies targeted against the various cell surface antigens. Following red cell lysis, the sample is passed through a flow cytometer. Using a CD45 vs side scatter gating technique, lymphocytes are selected and percentages of the various cell surface markers (CD3, CD4, CD8, CD19, CD16/CD56, CD4RA, CD4RO, CD8RA, and CD8RO) are determined. The absolute cell count of each marker (ie, the number of cells bearing each marker) is calculated using the absolute lymphocyte count (obtained from standard hematology instrumentation) and the marker percentage. Both the absolute cell count and the percentage are reported for each marker.

Quest Diagnostics offers the lymphocyte subset panels listed in the Table.

Interpretive Information

In patients with HIV infection, the CD4+ T-cell level and the CD4+/CD8+ ratio typically decline shortly after seroconversion. CD4+ levels above 500 cells/mm3 are usually associated with asymptomatic infection, whereas levels <200 cells/ mm3 are consistent with a transition to AIDS. CD4+ levels rise in response to effective anti-retroviral therapy. Aside from a history of AIDS-defining illness or severe HIV-related symptoms, the CD4+ cell count is generally the most important factor in determining when to initiate therapy. Therapy should be considered for patients with a CD4+ cell count ≤350 cells/mm3.

Identifying deficiency in T, B, or NK cells allows classification of SCID and other immunodeficiencies into one of the following types: T+B+NK+, T+B+NK-, T+B-NK+, T-B+NK+, T+B-NK-, T-B+NK-, T-B-NK+, and T-B-NK-. Such classification facilitates appropriate genetic counseling and clinical management.

 

Content reviewed 04/2013

 
top of page

* The tests listed by specialist are a select group of tests offered. For a complete list of Quest Diagnostics tests, please refer to our Directory of Services.