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HelpTest Code LAB1231797 X-Linked Hyper IgM Syndrome, Blood
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Reporting Name
X-Linked Hyper IgM Syndrome, BSpecimen Type
WB Sodium HeparinShipping Instructions
Testing is not performed on Saturday, Sunday, or observed holidays. Only collect and ship specimens for arrival on days when testing is performed.
Specimens received on days when testing is not performed or after 5 p.m. Central on Friday will be canceled if specimen is outside of stability when testing is next performed.
Collect and package specimen as close to shipping time as possible. It is recommended that specimens arrive within 24 hours of collection.
Necessary Information
The ordering healthcare professional's name and phone number are required.
Specimen Required
Container/Tube: Green top (sodium heparin)
Specimen Volume: 4 mL
Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.
Additional Information: For serial monitoring, it is recommended that specimen collection be performed at the same time of day.
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| WB Sodium Heparin | Ambient | 72 hours | GREEN TOP/HEP |
Specimen Minimum Volume
1.2 mL
Day(s) Performed
Monday through Friday
Specimen Retention Time
4 daysReport Available
3 to 4 daysReference Values
Present
Useful For
Screening for X-linked hyper-IgM (XL-HIGM) or CD40L deficiency, primarily in male patients younger than 10 years
Ascertaining XL-HIGM carrier status in women of child-bearing age (younger than 45 years)
CPT Code Information
88184-Flow cytometry, cell surface, cytoplasmic
88185 x 6-Each additional marker
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| XHIM | X-Linked Hyper IgM Syndrome, B | 98239-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 82964 | CD40 Ligand Expression | 98240-5 |
| 29040 | CD40muIg (Function) | 98241-3 |
| 23901 | Interpretation | 69052-9 |
Method Description
The assay measures the expression of CD40L on activated CD4 T cells. Heparinized whole blood is incubated with phorbol myristate acetate (PMA) and ionomycin (calcium ionophore) for lymphocyte activation. The red blood cells are lysed, and the remaining white blood cells are stained with a 4-color panel of antibodies on a single platform. The assay involves 4 tubes, which include an unstimulated control for both the CD40L and CD40-uIg antibodies. CD69 expression is measured as a positive control for appropriate T-cell activation. A combination of CD3, CD8, CD154 (CD40L), and CD40-uIg antibodies enables assessment of CD40L expression and binding (with CD40-uIg) on total T cells (CD3+), suppressor T cells (CD3+CD8+), and helper T cells (CD3+CD8-). A normal, healthy control will be included with each experiment to ensure the optimal performance of the assay.(O'Gorman MR, Zaas D, Paniagua M, et al, Development of a rapid whole blood flow cytometry procedure for the diagnosis of X-linked hyper-IgM syndrome patients and carriers. Clin Immunol Immunopathol. 1997;85[2]:179-181; Unpublished Mayo method)
Genetics Test Information
CD40LG is located on the long arm of the X-chromosome (Xq 21.3-22) and encodes the surface protein CD40 ligand (CD154). It is critical for the formation of germinal centers and, therefore, class switch recombination and somatic hypermutation. More than 100 unique genetic variants of CD40LG have been described. The observed variants are scattered throughout the gene but are more prevalent in exon 5.