Background:
B-cell lymphomas account for greater than 90% of non-Hodgkin lymphomas and may pose a diagnostic challenge on the basis of histopathology alone. During normal B-cell maturation, the immunoglobulin heavy chain gene is rearranged such that each mature B-cell and plasma cell has a unique rearranged heavy chain gene profile. This process is vital to proliferation of B-cells in normal immune function, but can be exploited to aid in the distinction between reactive (benign) versus neoplastic processes of B-cell proliferation. A reactive, benign B-cell proliferation is characterized by polyclonal expansion of B-cells whereas a malignant process is often characterized by a clonal expansion of a predominant B-cell population. In conjunction with histopathology study of lymph nodes, bone marrow and other tissue types, the detection of a clonal immunoglobulin heavy chain gene rearrangement by polymerase chain reaction (PCR) is intended as an aid in the diagnosis of malignant B-cell lymphoma.
T-cell lymphomas account for approximately 15% of non-Hodgkin lymphomas and may pose a diagnostic challenge on the basis of histopathology alone and particularly in early stages of disease. The heterodimeric T-cell surface receptors, either alpha/beta (90% -95% of T cells) or gamma/delta (5% - 10% of T cells) are produced following somatic rearrangement of the T-cell receptor (TCR) genes (alpha, beta, delta, and gamma). This process is vital to proliferation of T-cells in normal immune function, but can be exploited to aid in the distinction between reactive (benign) versus neoplastic processes of T-cell proliferation. A reactive, benign T-cell proliferation is characterized by polyclonal expansion of T-cells whereas a malignant process is characterized by clonal expansion of one T-cell population. In conjunction with morphologic evaluation of lymph nodes, bone marrow and other tissue types the detection of a clonal T-cell gene rearrangement by polymerase chain reaction (PCR) can be used to aid a diagnosis of malignant T-cell lymphoma.
Clinical Utility:
If the immunophenotype of the suspected lymphoproliferative process cannot be accurately determined by other methods, PCR-based studies for both T and B cell gene rearrangements can be performed simultaneously. The presence of a clonal immunoglobulin (B cell) or T cell receptor (T cell) gene rearrangement is usually (but not always) indicative of a neoplastic process.
Methodology:
Genomic DNA is extracted from blood, lymph node, bone marrow, or other tissue types and the rearranged immunoglobulin heavy chain, T-cell gamma, and T-cell bets genes are amplified by PCR using a multiplex primer method based on the BIOMED-2 strategy. Precise fragment sizing of the amplicons is accomplished using capillary gel electrophoresis. The presence or absence of a monoclonal population is determined based on the overall analysis of the gel electrophoretic pattern.
Specimen Requirements:
- 5-10 mL of blood or bone marrow — yellow (ACD) or purple (EDTA) tube;
- If sending DNA, please send 200ng at minimum of 10ng/µL (DNA must be extracted in a CLIA-certified laboratory or a laboratory meeting equivalent requirements as determined by the CAP and/or CMS)
- Formalin-fixed paraffin-embedded (FFPE) tissue block or 10 slides (5 micron)
- Fresh Tissue:
- Stabilize in Allprotect Tissue Reagent (Qiagen) and ship at room temperature – OR
- Suspend in sterile culture media (RPMI or DMEM) or non-bacteriostatic normal saline in a sterile container and shipped at room temperature – OR
- Snap Frozen and shipped on dry ice
- Pathology report MUST accompany sample for interpretation of results.
A REQUISITION FORM MUST ACCOMPANY ALL SAMPLES. Please include detailed clinical information.
Test Performed (Days):
Twice per week
Turn Around Time:
5-10 days
Shipment Sensitivity Requirements:
- Package and ship specimen to remain cold, but not frozen.
- Ship via overnight express, using the FedEx priority overnight label provided.
- Contact Client Services for shipping kits and instructions at (855) 535-1522.
References:
- Van Dongen JJ, Langerak AW, Bruggemann M, et al. Design and standardization of PCR primers and protocols for detection of clonal immunoglobulin and T-cell receptor gene recombinations in suspect lymphoproliferations: report of the BIOMED-2 Concerted Action BMH4-CT98-3936. Leukemia 2003; 17(12):2257-2317.
- Langerak AW, Molina TJ, Lavender FL, et al. Polymerase chain reaction-based clonality testing in tissue samples with reactive lymphoproliferations: usefulness and pitfalls. Report of the BIOMED-2 Concerted Action BMH4-CT98-3936. Leukemia 2007; 21:222-229.
Additional Info:
Please see test information for B-Cell Gene Rearrangement (test code 4070) and T-Cell Receptor Gene Rearrangement (test code 5592).