Test Catalog

Test ID: TCRVB    
TCR V-Beta Repertoire Analysis by Spectratyping, Blood

Method Description Describes how the test is performed and provides a method-specific reference

CD3+ T cells are enriched and purified from EDTA whole blood. RNA is obtained from the T cells and converted into cDNA to maximize sample stability. The cDNA is amplified using the polymerase chain reaction (PCR), during which the different CDR3 fragment lengths of the TCR Vb families are fluorescently labeled. The pool of varying CDR3 fragment lengths are separated by size on a capillary electrophoresis genetic analyzer. As the fluorescent label of each CDR3 fragment passes through the laser, the size and fluorescent intensity is recorded. The resulting image is a cluster of fluorescent peaks with single-base-pair separation and different fluorescent intensities, approximately corresponding to the number of fragments of that size represented in the patient’s original RNA. The peak patterns are reviewed for organization (number of peaks), relative intensity across peaks, and size distribution. The number of individual peaks is compared to a reference range established from over 140 healthy donors equally represented by both genders and across the pediatric and adult age spectrum. The reporting units are normalized among the patient population by using a diversity ratio for each TCR V beta family. The diversity ratio for each Vb family is determined by the number of peaks in that specific family relative to all peaks within the patient's sample expressed as a percentage. The analytical process in the laboratory utilizes a variety of controls to assess the performance of the assay and reliability of the result provided. The fragment length analysis is performed by the Gene Marker software and the spectratype is assembled for interpretation. An interpretive report will be provided for each patient sample and includes information on the diversity ratio for each family. The spectratype will be made available on request of the physician.(Unpublished Mayo method)

PDF Report Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.


Do not draw specimen after Thursday. Specimen must be received by 10 a.m. on Friday.

Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.

10 days

Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Clinic Laboratories until the release of the test result

14 days

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

Extracted DNA: 2 months

Performing Laboratory Location Indicates the location of the laboratory that performs the test