Test Catalog

Test Id : XHIM

X-Linked Hyper IgM Syndrome, Blood

Useful For
Suggests clinical disorders or settings where the test may be helpful

Screening for X-linked hyper-IgM (XL-HIGM) or CD40L deficiency, primarily in male patients younger than 10 years of age

 

Ascertaining XL-HIGM carrier status in women of child-bearing age (younger than 45 years old)

Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request

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.

Method Name
A short description of the method used to perform the test

Flow Cytometry

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

No

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

X-Linked Hyper IgM Syndrome, B

Aliases
Lists additional common names for a test, as an aid in searching

CD154

CD40 Activation

CD40 Ligand

Memory Cells

T cell Activation

IgM (Immunoglobulin)

Specimen Type
Describes the specimen type validated for testing

WB Sodium Heparin

Shipping Instructions

Specimens are required to be received in the laboratory weekdays and by 4 p.m. on Friday. Collect and package specimen as close to shipping time as possible.

 

It is recommended that specimens arrive within 24 hours of collection.

 

Specimens arriving on the weekend and observed holidays may be canceled.

 

Specimens received more than 72 hours after collection will be rejected and the assay will not be performed.

Necessary Information

Ordering physician's name and phone number are required.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Container/Tube: Green top (sodium heparin)

Specimen Volume: 4 mL

Collection Instructions: Send 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.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

1.2 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
WB Sodium Heparin Ambient (preferred) 72 hours GREEN TOP/HEP

Useful For
Suggests clinical disorders or settings where the test may be helpful

Screening for X-linked hyper-IgM (XL-HIGM) or CD40L deficiency, primarily in male patients younger than 10 years of age

 

Ascertaining XL-HIGM carrier status in women of child-bearing age (younger than 45 years old)

Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request

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.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

CD154 (CD40 ligand: CD40L) is required for the interaction of T cells and B cells as part of the normal adaptive immune response. Activation of T cells leads to the expression of the CD40L molecule on the cell surface. CD40L binds the CD40 receptor that is always present on B cells, monocytes, and macrophages (regardless of environmental conditions). Interaction of CD40L with CD40 is important in B-cell proliferation, differentiation, and class-switch recombination (isotype class-switching).

 

Patients with X-linked hyper-IgM (XL-HIGM) syndrome have defective CD40L expression on their activated helper CD4 T cells.(1,2) It is the most common class switch recombination defect and accounts for approximately 50% of the patients in this category. It leads to defective B-cell responses and the absence of immunoglobulin class-switching, which are typified by a profound reduction or absence of isotype class-switched memory B cells (CD19+CD27+IgM-IgD-) with low or absent secreted IgG and IgA and normal or elevated serum IgM levels.(1,2) Due to the impairment of T-cell function and macrophage activation, patients with XL-HIGM are particularly prone to opportunistic infections with Pneumocystis jiroveci, Cryptosporidium, and Toxoplasma gondii.(1)

 

A defect in surface expression of CD40L on activated CD4 T cells can be demonstrated using an anti-CD40L antibody and flow cytometry.(3,4) Since certain CD40LG variants can maintain surface protein expression, albeit with loss of function, it is important to also evaluate CD40L-binding capacity to eliminate the possibility of false-negative results. A soluble recombinant, chimeric receptor protein, CD40-uIg, is incorporated into the assay, which assesses CD40L function by determining receptor-binding activity. Approximately 20% of patients with XL-HIGM have activated CD4 T cells with normal surface expression of CD40L but aberrant function.(4)

 

XL-HIGM is a severe primary immunodeficiency that affects male patients, and most patients are diagnosed within a few months to the first year of life. Female patients are typically carriers and asymptomatic. Consequently, this test is only indicated for boys (<10 years of age) or, to identify carriers, for women of child-bearing age (<45 years).

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Present

Interpretation
Provides information to assist in interpretation of the test results

This is a qualitative assay; CD40L-protein expression and function are reported as present or absent. Absence of CD40L-protein expression and function is consistent with X-linked hyper-IgM (XL-HIGM). In female patients, the presence of 2 populations-normal and abnormal-is consistent with carrier status.

 

Most patients (80%-90%) with XL-HIGM have absent or significantly reduced CD40L expression on their activated CD4 T cells. Patients with normal CD40L expression, but abnormal function, show an absence of binding with soluble chimeric CD40-uIg antibody, substantiating a diagnosis of XL-HIGM. Female patients who are carriers for this disease will show a typical bimodal pattern of CD40L expression, with 50% of the T cells lacking any CD40L expression. In the case of aberrant protein function, a similar profile will be obtained with the CD40-uIg antibody.

 

CD69 is a marker for T-cell activation and serves as a positive control; in the absence of induced CD69 expression on T cells, the presence of XL-HIGM cannot be assessed.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This test is typically not indicated in male patients over 10 years of age or women beyond child-bearing age (>45 years). For questions about appropriate test selection, call 800-533-1710.

 

The test must be performed on fresh, heparinized whole blood cells for appropriate CD40L expression on activated CD4 T cells; specimen handling instructions must be followed. T-cell activation is variable on specimens tested between 48 and 72 hours after blood collection. These specimens will be analyzed, and results will be reported after the laboratory director's review.

 

Patients with normal CD40L expression and normal receptor binding with the CD40-uIg antibody, yet presenting with the clinical phenotype of hyper-IgM (HIGM) syndrome, should be evaluated for autosomal recessive forms of this syndrome including mutations in CD40, AICDA (AID), and UNG.(1,2) A combination of clinical features and laboratory analyses should permit identification of an underlying HIGM defect, if present.

 

The other form of X-linked hyper-IgM (XL-HIGM) involving variants in the NEMO (NF-kappa B essential modulator) gene (official symbol IKBKG) can be easily discriminated from the CD40LG deficiency due to the unusual and characteristic clinical findings including abnormal development of ectoderm-derived skin structures and immunodeficiency with increased susceptibility to mycobacterial infections.(1,2)

 

Previous studies have reported variants involving splice sites that result in the generation of small amounts of wild-type CD40L, associated with a milder clinical phenotype.(4) In these cases, the CD40-uIg fusion protein may show some binding, albeit at lower intensity and, therefore, the final molecular diagnosis depends on sequencing of the CD40LG gene.

 

This is not a confirmatory test for CD40L deficiency, and genetic testing must be performed to determine the specific variant involved. Information about genetic testing for CD40L deficiency is available by calling 800-533-1710.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Etzioni A, Ochs HD: The hyper IgM syndrome-an evolving story. Pediatr Res. 2004 Oct:56(4):519-525

2. Durandy A, Peron S, Fischer A: Hyper-IgM syndromes. Curr Opin Rheumatol. 2006 Jul;18(4):369-376

3. Lee WI, Torgerson TR, Schumacher MJ, Yel L, Zhu Q, Ochs HD: Molecular analysis of a large cohort of patients with the hyper immunoglobulin M (IgM) syndrome. Blood. 2005 Mar 1;105(5):1881-1890

4. Seyama K, Nonoyama S, Gangsaas I, et al: Mutations of the CD40 ligand gene and its effect on CD40 ligand expression in patients with X-linked hyper IgM syndrome. Blood. 1998 Oct;92(7):2421-2434

5. Vargas-Hernandez A, Berron-Ruiz L, Staines-Boone T, et al: Clinical and genetic analysis of patients with X-linked hyper-IgM syndrome. Clin Genet. 2013 Jun;83(6):585-587

6. Vavassori V, Mercuri E, Marcovecchio GE, et al: Modeling, optimization, and comparable efficacy of T cell and hematopoietic stem cell gene editing for treating hyper-IgM syndrome. EMBO Mol Med. 2021 Mar 5;13(3):e13545

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

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 Nov;85[2]:179-181; Unpublished Mayo method)

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

No

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

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

3 to 4 days

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

4 days

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

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

88184-Flow cytometry, cell surface, cytoplasmic

88185 x 6-Each additional marker

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

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
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
29040 CD40muIg (Function) 98241-3
82964 CD40 Ligand Expression 98240-5
23901 Interpretation 69052-9

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports