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HelpTest Code LAD1 Leukocyte Adhesion Deficiency Type 1, CD11a/CD18 and CD11b/CD18 Complex Immunophenotyping, Blood
Reporting Name
Leukocyte Adhesion Def. Type 1, BUseful For
Aiding in the diagnosis of leukocyte adhesion deficiency syndrome type 1, primarily in patients younger than 18 years
CD11a, CD11b, and CD18 phenotyping
Method Name
Flow Cytometric Immunophenotyping
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Whole Blood EDTAShipping Instructions
Testing is performed Monday through Friday. Specimens not received by 4 p.m. (CST) on Friday may be canceled.
Draw and package specimen as close to shipping time as possible. It is recommended that specimens arrive within 24 hours of draw.
Specimens arriving on the weekend and observed holidays may be canceled.
Necessary Information
Date and time of collection and healthcare professional name and phone number are required.
Specimen Required
Container/Tube: Lavender top (EDTA)
Specimen Volume: 5 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
2 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
Normal (reported as normal or absent expression for each marker)
Day(s) Performed
Monday through Friday
CPT Code Information
86356 x 3
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| LAD1 | Leukocyte Adhesion Def. Type 1, B | 94266-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 81155 | Leukocyte Adhesion Deficiency, B | No LOINC Needed |
| 430 | CD11a | 94268-0 |
| 388 | CD11b | 94267-2 |
| 431 | CD18 | 94265-6 |
| 432 | LAD Interpretation | 69052-9 |
Clinical Information
Leukocyte adhesion deficiency syndrome type 1 (LAD-1) is an autosomal recessive disorder caused by variants in the common chain (CD18) of the beta2-integrin family. LAD-1 is clinically characterized by recurrent infections, impaired wound healing, delayed umbilical cord separation, persistent leukocytosis, and recurrent soft tissue and oral infections.
Each of the beta2-integrins is a heterodimer composed of an alpha chain (CD11a, CD11b, or CD11c) noncovalently linked to a common beta2-subunit (CD18). The alpha-beta heterodimers of the beta2-integrin family include lymphocyte function-associated antigen 1 (CD11a/CD18), Mac-1/CR3 (CD11b/CD18), and p150/95 (CD11c/CD18).(1-4) The CD18 gene, ITGB2, and its product are required for normal expression of the alpha-beta heterodimers. Therefore, defects in CD18 expression lead to either very low or no surface membrane expression of CD11a, CD11b, and CD11c.
Severe and moderate forms of LAD-1 exist, differing in the degrees of protein deficiency, which are caused by different ITGB2 variants. Two relatively distinct clinical phenotypes of LAD-1 have been described. Patients with the severe phenotype (<1% of normal expression of CD18 on neutrophils) characteristically have delayed umbilical stump separation (>30 days), infection of the umbilical stump (omphalitis), persistent leukocytosis (>15,000/microliter) in the absence of overt active infection, and severe destructive gingivitis with periodontitis and associated tooth loss, and alveolar bone resorption. Patients with the moderate phenotype of LAD-1 (1%-30% of normal expression of CD18 on neutrophils) tend to be diagnosed later in life. Normal umbilical separation, lower risk of life-threatening infections, and longer life expectancy are common in these patients. However, leukocytosis, periodontal disease, and delayed wound healing are still very significant clinical features.
Patients with LAD-1 (and other primary immunodeficiency diseases) are unlikely to remain undiagnosed in adulthood. Consequently, this test should not be typically ordered in adults for LAD-1. However, it may be also used to assess immune competence by determining CD18, 11a, and 11b expression.
Interpretation
The report will include a summary interpretation of the presence or reduction in the level of expression of the individual markers (CD11a, CD11b, and CD18). Expression of the individual markers provides indirect information on the presence or absence of the CD11a/CD18 and CD11b/CD18 complexes.
Specimens obtained from patients with leukocyte adhesion deficiency syndrome type 1 (LAD-1) show significant reduction (moderate phenotype) or near absence (severe phenotype) of CD18 and its associated molecules, CD11a and CD11b, on neutrophils and other leukocytes.
CD11c expression also is low in LAD-1. The analytical sensitivity of the CD11c assay is insufficient to allow interpretation of CD11c surface expression. Therefore, this test is only for the expression of CD18, CD11a, and CD11b.
Cautions
This test is typically not indicated in adults. For questions about appropriate test selection, call 800-533-1710.
Patients with normal beta2-integrin expression without functional activity have been described.(5-6) Therefore, expression of CD18 alone is insufficient to exclude the diagnosis of leukocyte adhesion deficiency syndrome type 1; functional assays (eg, neutrophil chemotaxis, random migration assays) must be performed if the clinical suspicion is high.
Method Description
Flow cytometric immunophenotyping of peripheral blood is performed to evaluate the presence or absence of the CD11/CD18 complex using monoclonal antibodies directed against the CD11 isoforms, CD11a and CD11b, and CD18 antigens.(O'Gorman MR, McNally AC, Anderson DC, et al. A rapid whole blood lysis technique for the diagnosis of moderate or severe leukocyte adhesion deficiency [LAD]. Ann NY Acad Sci. 1993;677:427-430)
Report Available
3 to 4 daysTest 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.Genetics Test Information
ITGB2 is located on the long arm of chromosome 21(21q22.3). It encodes the common beta 2 integrin subunit (CD18), which is necessary for the expression of lymphocyte function-associated antigen 1 (CD11a/CD18), Mac-1/CR3 (CD11b/CD18), and p150/95 (CD11c/CD18).
Variants in this gene are the underlying cause for the autosomal recessive leukocyte adhesion deficiency type 1.