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TRBC1 a Useful Tool in T-Cell Flow Cytometry [A Test in Focus]

Flow cytometry is a well-established method that is utilized to assist in the characterization of mature T-cell neoplasms and lymphoproliferations, but the markers used by individual laboratories can vary. In this "Test in Focus," Horatiu Olteanu, M.D., Ph.D., gives an overview of the new T-cell receptor (TCR) β-chain constant region (TRBC1) flow cytometry marker, which is now included in Mayo Clinic Laboratories' routine diagnostic T-cell flow cytometry panel. He discusses when this testing should be ordered, how the addition of TCRBC1 compares to previous testing approaches, and how this marker can assist ordering physicians.

Testing

Useful for:

  • Evaluating lymphocytoses of undetermined etiology
  • Identifying T-cell lymphoproliferative disorders involving blood and bone marrow
  • Distinguishing reactive lymphocytes and lymphoid hyperplasia from malignant lymphoma
  • Distinguishing between malignant lymphoma and acute leukemia
  • T-cell large granular lymphocytic leukemia, peripheral T-cell lymphoma, not otherwise specified, anaplastic large T-cell lymphoma, angioimmunoblastic T-cell lymphoma, Sezary syndrome / mycosis fungoides, and certain T-lymphoblastic leukemia/lymphoma, among others.

Specimen Requirements

Specimen Type 

Varies

Specimen Required 

Submit only 1 of the following specimens:

Specimen Type: Blood

Container/Tube:

Preferred: Yellow top (ACD solution A or B)

Acceptable: Green top (sodium heparin) or lavender top (EDTA)

Specimen Volume: 6 mL

Slides: Include 5 to 10 unstained blood smears, if possible.

Collection Instructions:

1. Send specimen in original tube. Do not transfer blood to other containers.

2. Label specimen as blood.

Specimen Stability Information: Ambient <96 hours/Refrigerated < or =96 hours

Specimen Type: Bone marrow

Container/Tube:

Preferred: Yellow top (ACD solution A or B)

Acceptable: Green top (sodium heparin) or lavender top (EDTA)

Specimen Volume: 1-5 mL

Slides: Include 5 to 10 unstained bone marrow aspirate smears, if possible.

Collection Instructions:

1. Submission of bilateral specimens is not required.

2. Label specimen as bone marrow.

Specimen Stability Information: Ambient <96 hours/Refrigerated < or =96 hours

Specimen Type: Fluid

Sources: Serous effusions, pleural fluid, pericardial fluid, abdominal (peritoneal) fluid

Container/Tube: Body fluid container

Specimen Volume: 20 mL

Collection Instructions:

1. If possible, fluids other than spinal fluid should be anticoagulated with heparin (1 U/mL of fluid).

2. The volume of fluid necessary to phenotype the lymphocytes or blasts in serous effusions depends upon the cell count in the specimen. Usually 20 mL of pleural or peritoneal fluid is sufficient. Smaller volumes can be used if there is a high cell count.

3. Label specimen with fluid type.

Specimen Stability Information: Refrigerated <72 hours/Ambient < or =72 hours

Specimen Type: Spinal fluid

Container/Tube: Sterile vial

Specimen Volume: 1-1.5 mL

Collection Instructions:

1.An original cytospin preparation (preferably unstained) must be included with the spinal fluid specimen so correlative morphologic evaluation can occur.

2. The volume of fluid necessary to phenotype the lymphocytes or blasts in spinal fluid depends upon the cell count in the specimen. A cell count should be determined and submitted with the specimen. Usually 1 to 1.5 mL of spinal fluid is sufficient. Smaller volumes can be used if there is a high cell count. If cell count is <10 cells/mcL, a larger volume of spinal fluid may be required. When cell counts drop below 5 cells/mcL, the immunophenotypic analysis may not be successful.

3. Label specimen as spinal fluid.

Specimen Stability Information: Refrigerated <48 hours/Ambient < or =48 hours

Performance Information

Day(s) and Time(s) Test Performed 

Specimens are processed and reported Monday through Saturday

Analytic Time 

1 day

Additional Resources

Alyssa Frank

Alyssa Frank

Alyssa Frank is a Marketing Segment Manager at Mayo Clinic Laboratories. She leads marketing strategies for product management and specialty testing. Alyssa has worked at Mayo Clinic since 2015.