Lymphocyte immunophenotyping
Last updated: Friday, 04, June, 2010
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| Item | Process |
|---|---|
| Specimen | 5-10 mL blood in lithium heparin, ACD or EDTA. |
| Method | Blood incubated with fluorescent labelled monoclonal antibodies directed against specific lymphocyte surface antigens. Detection of these antigens allows quantitation of total B cell numbers (CD19) and total T cell numbers (CD3), identification and quantitation of T cell subsets (CD4, CD8) and natural killer (NK) cells (CD16). Cells are enumerated by flow cytometry. |
| Reference Interval | Affected by age and gender, diurnal rhythm and other physiological variables - consult pathologist. See Table 5. |
| Application | Assessment of immune deficiency states, lymphocytosis of unknown aetiology, diagnosis of lymphoid malignancies. More extensive 'flow cytometry' analysis is required for investigation of haematological malignancies. |
| Interpretation | Lymphocyte numbers are interpreted in conjunction with clinical findings, lymphocyte morphology and other immune measurements. In HIV infection, low absolute CD4 count (<0.35 x 109/L) is predictive of disease progression, and <0.20 x 109/L CD4 is associated with an increased risk of opportunistic infection. T cells are increased in reactive disorders and in some infections (eg, infectious mononucleosis). B cells (CD19) are absent in X-linked hypogammaglobulinaemia but are usually present in common variable immunodeficiency. Increased B cell numbers occur in B cell proliferative diseases; monoclonality suggests leukaemia/lymphoma. NK (CD16) cell numbers are reduced in some immunocompromised patients, patients with cancer, and in Chediak Higashi syndrome. NK cells may be increased in reactive conditions, hepatitis C virus infection, IV drug abuse, lymphomas. See also Flow cytometry, Table 1., Table 2. |
| Reference | McCarthy DA and Macey MG. Cytometric Analysis of Cell Phenotype and Function. Cambridge University Press 2002. |