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HelpTest Code ALPS Alpha Beta Double-Negative T Cells for Autoimmune Lymphoproliferative Syndrome, Blood
Reporting Name
ALPS ScreenUseful For
Diagnosing autoimmune lymphoproliferative syndrome, primarily in patients younger than 45 years
Method Name
Flow Cytometry
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Whole Blood EDTAShipping Instructions
Testing is performed Monday through Friday. Specimens not received by 4pm (CST) on Friday may be canceled.
Collect and package specimen as close to shipping time as possible. It is recommended that specimens arrive within 24 hours of collection.
Samples arriving on the weekend and observed holidays may be canceled.
Necessary Information
Ordering healthcare professional name and phone number are required.
Specimen Required
Container/Tube: Lavender top (EDTA)
Specimen Volume: 3 mL
Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.
Additional Information: For serial monitoring, it is recommended that specimens are collected at the same time of day.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole Blood EDTA | Ambient | 72 hours | PURPLE OR PINK TOP/EDTA |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
Reference Values
Alpha beta TCR+DNT cells
2-18 years: <2% CD3 T cells
19-70+ years: <3% CD3 T cells
Reference values have not been established for patients that are younger than 24 months of age.
Alpha beta TCR+DNT cells
2-18 years: <35 cells/mcL
19-70+ years: <35 cells/mcL
Reference values have not been established for patients that are younger than 24 months of age.
Alpha beta TCR+DNT B220+ cells
2-18 years: <0.4% CD3 T cells
19-70+ years: <0.3% CD3 T cells
Reference values have not been established for patients that are younger than 24 months of age.
Alpha beta TCR+DNT B220+ cells
2-18 years: <7 cells/mcL
19-70+ years: <6 cells/mcL
Reference values have not been established for patients that are younger than 24 months of age.
TCR = T-cell receptor
DNT = Double negative T cell
Day(s) Performed
Monday through Friday
CPT Code Information
86356 x2
86359
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| ALPS | ALPS Screen | 101414-1 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 23973 | %alpha/beta-TCR DNT | 34962-1 |
| 23974 | alpha/beta-TCR DNT | 34963-9 |
| 28904 | % TCR+DNT B220+ | 88052-6 |
| 28905 | Absolute TCR+DNT B220+ | 88053-4 |
| 23975 | Interpretation | 69052-9 |
Test Classification
This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.Clinical Information
Autoimmune lymphoproliferative syndrome (ALPS) (also known as Canale-Smith syndrome) is a complex clinical disorder of dysregulated lymphocyte homeostasis that is characterized by lymphoproliferative disease, autoimmune cytopenias, splenomegaly, and lymphadenopathy with an increased susceptibility to malignancy.(1) Typically, ALPS is diagnosed by childhood or young adulthood.
Genetic defects in the apoptosis (programmed cell death) pathway have been determined for most cases of ALPS. Apoptosis plays a role in normal immune homeostasis by limiting lymphocyte accumulation and autoimmune reactivity. The interaction of the surface receptor CD95 (FAS) and its ligand (CD95L; FASL) triggers the apoptotic pathway in lymphocytes. Germline variants in CD95 (FAS) are the most common cause (60-75%) of ALPS(2), followed by somatic mutations in CD95 (FAS). Variants in CD95L (FASL), CASP10, and others are rare causes. Currently up to 20% of patients do not have an identifiable genetic variant (ALPS-U).
Patients with ALPS have an increase in a normally rare population of T cells (typically <1%) that are alpha beta T-cell receptor (TCR)-positive, as well as negative for both CD4 and CD8 coreceptors (double-negative T cells: DNT).(1) The alpha beta TCR+DNT cells from ALPS patients may also express an unusual B-cell-specific CD45R isoform, called B220.(3,4)
Several other diseases can present with an ALPS-like phenotype, including other inborn errors of immunity, like CTLA4 and LRBA deficiency, and gain-of function variants in STAT3 and CARD11 genes(2,5), as well as independent conditions like Evans syndrome (a combination of autoimmune hemolytic anemia and autoimmune thrombocytopenic purpura), Rosai-Dorfman disease (massive painless cervical lymphadenopathy that may be accompanied by leukocytosis, elevated erythrocyte sedimentation rate, and hypergammaglobulinemia), and nodular lymphocyte-predominant Hodgkin disease, among others.(1,2,5) B220 expression on double negative T cells has also been described in large granular lymphocyte leukemias.(4)
Interpretation
The presence of increased circulating T cells (CD3+) that are negative for CD4 and CD8 (double-negative T cells: DNT) and positive for the alpha/beta T-cell receptor (TCR) is required for the diagnosis of autoimmune lymphoproliferative syndrome (ALPS).
The laboratory finding of increased alpha beta TCR+DNT cells is consistent with ALPS only with the appropriate clinical picture (nonmalignant lymphadenopathy, splenomegaly, and autoimmune cytopenias). Conversely, there are other immunological disorders, including common variable immunodeficiency (CVID), which have subsets for patients with this clinical picture, but no increase in alpha beta TCR+DNT cells.
If the percent of the absolute count of either the alpha beta TCR+DNT cells or alpha beta TCR+DNT B220+ cells is abnormal, additional testing is indicated. All abnormal alpha beta TCR+DNT cell results should be confirmed (for ALPS) with additional testing for defective in vitro lymphocyte apoptosis followed by confirmatory genetic testing (ALPSG / Autoimmune Lymphoproliferative Syndrome [ALPS] Gene Panel, Varies).
Cautions
This test is typically not indicated in older adults. For questions about appropriate test selection, call 800-533-1710.
The sole presence of increased alpha beta T-cell receptor + double-negative T cells B220+ cells is not sufficient for a diagnosis of autoimmune lymphoproliferative syndrome (ALPS); additional testing is required to confirm a diagnosis of ALPS.
Method Description
This assay uses a 5-color, single-platform method with a 2-tube panel stained for the following antibodies: CD3, CD4, CD8, CD45, alpha beta T-cell receptor, and B220. The sample is stained with the antibody cocktail and incubated in the dark at room temperature for 20 minutes. Following incubation, the samples are treated with BD lysing solution to lyse the red blood cells followed with a wash step using BD FACS wash buffer. The cells are resuspended in 1% paraformaldehyde and analyzed by flow cytometry. The different subsets are expressed as a percent of CD3 T cells, and the absolute counts of all subsets are expressed as cells/mcL.(Unpublished Mayo method)
Report Available
3 to 4 daysSpecimen Retention Time
4 daysForms
If not ordering electronically, complete, print, and send a Benign Hematology Test Request Form (T755) with the specimen.