T and B LYMPHOCYTE SUBSET ASAAY

Sample type:

Whole Blood EDTA

Uses:

• Serial monitoring of CD4 T-cell count in HIV-positive patients

• Follow-up and diagnostic evaluation of primary immunodeficiencies, including severe combined immunodeficiency

• Immune monitoring following immunosuppressive therapy for transplantation, autoimmunity, and other immunological conditions where such treatment is utilized

• Assessment of immune reconstitution post hematopoietic cell transplantation

• Early screening of gross quantitative anomalies in lymphocyte subsets in infection or malignancies

• Absolute quantitation of circulating B cells for diagnosis of chronic lymphocytic leukemia patients as indicated in the 2008 International Workshop on Chronic Lymphocytic Leukemia guidelines

Precautions:

Lymphocyte subset counts should be appropriately interpreted in context of the clinical presentation and other immunological parameters and relevant laboratory test results.

For serial monitoring of lymphocyte subsets it is recommended that the patient be evaluated at the same time of the day to account for diurnal variation.

While this assay can be used to follow patients on B-cell-depleting therapy, like Rituximab or Ofatumumab, it may be more reasonable and financially viable to use CD20B / CD20 on B Cells (includes CD45, CD19 and CD20 markers).

Interfering factor:

1 . Interferences that alter the measurable analyte concentration in the sample

• Hormone binding proteins

• Pre-analytical factors, e.g., anticoagulants, sample storage

• Autoanalyte antibodies

2 . Interferences that alter antibody binding

• Heterophile antibodies

• Human anti-animal antibodies

• High-dose hook effect

Pre analytical errors:

Binding of cations present in serum, e.g., Mg2+ or Ca2+, to drugs or proteins can change antigen conformation and the measurable analyte concentration.

Sample type can affect analyte concentration with differences in results for samples collected in lithium heparin, EDTA, and sodium fluoride/potassium oxalate or tubes without anticoagulant reported for some analytes, e.g., cardiac troponin, hormones.

Corrective action:

Standardized procedures for assessing haemolysed or lipaemic specimens Awareness of assay characteristics Protocols for assessing possible interference Established protocol for vulnerable analytes (e.g. tumour markers)

Establishing good communication with clinical staff and technical staff in relevant diagnostic companies

Post analytical errors:

• Processing of results for transcription onto report forms

• Reduce human error through root-cause analysis, process control, and education/communication

Reference range:

The lymphocyte reference ranges percentages [absolute counts - Abs, cells/μl] unadjusted for gender differences for adolescents are: CD3: 49-83 [939-2959]; CD4: 27-53 [467-1563]; CD8: 16-40 [259-1262]; CD19+ B cells: 8-31 [169-1297] and CD16+CD56+ NK cells: 3-30 [59-1178] and for adults are: CD3: 65-88 [983-3572]; CD4: 26-62 [491-2000]; CD8: 14-44 [314-2,087]; CD19+ B cells: 2-27 [64-800] and CD16+CD56+ NK cells: 2-27 [27-693].