Lymphocyte Subsets

Description: Distinct lymphocyte subsets including T-cells, B-cells, and natural killer (NK) cells are identifiable by characteristic cell surface marker molecules. T-cells are involved in cell mediated immunity, B-cells with humoural immunity and NK cells play a role in defence against viral infections and tumours. T-cells are CD3 positive, B-cells are CD19 positive, and NK cells are CD3 negative, CD16 and CD56 positive. T-cells are further classified as helper cells (CD4 positive,) or cytotoxic cells (CD8 positive,). In turn, CD4+ and CD8+ cells can be classified as naÃ¯ve (CD4RA+, CD8RA+) or memory cells (CD4RO+, CD8RO+). The absolute number and percentage of different lymphocyte subsets can vary in various diseases. For example, in individuals with human immunodeficiency virus (HIV) infection, the number of CD4+ cells and the CD4+: CD8+ ratio is affected by the stage of disease and response to treatment. Thus, lymphocyte subset analysis can provide information regarding the immune status of the HIV infected patient and assist in monitoring therapy. Characteristic lymphocyte subset profile can be seen in a number of primary immunodeficiency disorders. A specific test request for T-cell subsets only test for CD4 and CD8 lymphocytes and is used for monitoring anti-retroviral treatment and HIV infection.

Reference range: Lymphocytes CD 3 %, 55 - 83 Lymphocytes CD 3 absolute counts, 700 - 2100 Lymphycytes CD 4 %, 28 - 57 Lymphocytes CD 4 absolute counts, 300 - 1400 Lymphocytes CD 8 %, 10 - 39 Lymphocytes CD 8 absolute counts, 200 - 900 B cells CD19 %, 6 - 9 B cells absolute counts, 100 - 500 NK cells %, 7 - 31 NK cells absolute counts, 90 - 600

Sample type and volume required: 1 X Purple EDTA adult tubes or at least 1mL purple/pink paediatric tubes

Special sample instructions: Do not Refrigerate sample. Test is time sensitive and samples should be sent to the lab immediately. Please note there is no laboratory service during Fridays, weekend and bank holidays. Samples received during this period will not be processed.

Storage and transport: Samples must NOT be refrigerated. Please state time of venesection on the request form. Samples are suitable for analysis up to 72 hours post venesection. Samples that arrive in lab after 72 hours will not be analysed. Courier transport to deliver directly to the Immunology laboratory is recommended. Packaging and samples must be labelled as "urgent-time sensitive assay" , and addressed to attention to Immunology Department.

Last updated: 19 June 2026