• monitoring peripheral blood CD4 count in known HIV positive patients.

• See sheet on HIV / AIDS.

• Monitoring cytotoxic or immunosuppressive therapy.
• Monitoring recovery after bone marrow transplantation.
• Investigation of immunodeficiency.

• Enumerates total T cells (CD3), T cell subsets (CD4, CD8), total B cells (CD19) and total NK cells (CD16/56).
• SydPath reference intervals are for adults. Intervals are different in Children; see RCPA manual.
• CD4:CD8 ratio (reference range 1.4-3.7) is typically less than 1 in untreated HIV, EBV, CMV.
• CD8 count may be markedly elevated in viral infections, especially EBV.

• Suspected leukaemia / lymphoma
• Investigation of lymphocytosis
• Monitoring leukaemia / lymphoma
• As well as blood, can be performed on bone marrow aspirates, lymph node and other biopsies, fine needle aspirates, and pleural, peritoneal and other body fluids.

• Identifies cell lineage in leukaemia / lymphoma. Diagnosis should not be made on cell surface markers alone, but in conjunction with morphology, cytogenetics etc.
• Kappa and lambda light chains are routinely tested to determine clonality of B cell disorders; exclusive presence of either kappa or lambda on B cells indicates monoclonal population.
• Vbeta may be requested to determine clonality of T cell disorders; exclusive presence of one Vbeta on T cells indicates monoclonal population.
• Pathologists interpretation provided with reports.

Disorder: Immunophenotype

• B-CLL: B cells (CD19, 20 pos) with exclusive kappa or lambda and 4-5 of the following features: CD5 pos, CD22 dim/neg, CD23 pos, FMC7 neg and light chain dim. This phenotype, combined with an increased blood lymphocyte count and consistent clinical features, is sufficient for a diagnosis of B-CLL.
• B-Non Hodgkins Lymphoma: B cells (CD19, 20 pos_ wih kappa or lambda and 0-2 of the 5 B-CLL features listed above. (Cells with 3 of the 5 B-CLL features are difficult to classify). Confirmation of B-NHL diagnosis and further classification depends on a combination of clinical, histological and flow cytometry findings.
• B precursor ALL (commonALL): CD10 usually pos, CD19 pos, CD34 pos, HLA-DR pos, kappa / lambda neg.
• AML: One or more of CD11b, CD13 and CD33 are pos in the majority of cases; lymphoid markers are usually neg.