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HelpTest ID DHRF Dihydrorhodamine (DHR) Flow Cytometric N-Formyl-Methionyl-Leucyl-Phenylalanine (fMLP) Test, Blood
Useful For
Diagnosis of Rac2 deficiency
Method Name
Flow Cytometry
Reporting Name
DHR Flow fMLP, BSpecimen Type
WB Sodium HeparinSpecimens are required to be received in the laboratory weekdays and by 4 p.m. on Friday. It is recommended that specimens arrive within 24 hours of draw. Samples arriving on the weekend may be canceled. Draw and package specimen as close to shipping time as possible. Ship specimen overnight in an Ambient Mailer-Critical Specimens Only (Supply T668).
Ordering physician name and phone number are required.
A whole blood sodium heparin specimen and a whole blood sodium heparin control specimen from an unrelated, healthy donor are required.
Patient:
Container/Tube: Green top (sodium heparin)
Specimen Volume: 5 mL
Collection Instructions: Send specimen in original tube.
Normal Control:
Container/Tube: Green top (sodium heparin)
Specimen Volume: 5 mL
Collection Instructions:
1. Label clearly on outermost label normal control.
2. Send specimen in original tube.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| WB Sodium Heparin | Ambient | 48 hours |
Clinical Information
This assay can be used for the diagnostic evaluation of Rac2 deficiency, which is a neutrophil defect that causes profound neutrophil dysfunction with decreased chemotaxis, polarization, superoxide anion production, azurophilic granule secretion. This disease is caused by inhibitory mutations in the RAC2 gene, which encodes a Rho family GTPase essential to neutrophil activation and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase function.(1) Patients with Rac2 deficiency have been shown to have normal neutrophil oxidative burst when stimulated with phorbol myristate acetate (PMA), indicating normal NADPH oxidase activity, but abnormal neutrophil responses to N-formyl-methionyl-leucyl-phenylalanine (fMLP), which is a physiological activator of neutrophils. The defective oxidative burst to fMLP, but not to PMA, indicates a signaling defect in Rac2 deficiency.(2)
Reference Values
|
Result Name |
Unit |
Cutoff for defining normal |
|
% fMLP ox-DHR+ |
% |
≥10% |
|
MFI fMLP ox-DHR+ |
MFI |
≥2 |
|
Control % fMLP ox-DHR+ |
% |
≥10% |
|
Control MFI fMLP ox-DHR+ |
MFI |
≥2 |
The appropriate age-related reference values for Absolute Neutrophil Count will be provided on the report.
Cautions
Specimens are optimally tested within 24 hours of blood draw, though the stability of the assay is within 48 hours of collection. Specimens should be collected in sodium heparin and transported under strict ambient conditions. Use of the Ambient Mailer-Critical Specimens Only box (Supply T668) is encouraged to ensure appropriate transportation of the specimen.
Hemolyzed specimens may give high background. Specimens with an ANC (absolute neutrophil count) <200 will not be accepted for this assay. Complete myeloperoxidase (MPO) deficiency can yield a false-positive result.
Day(s) Performed
Monday through Friday
Specimen must be received by 4 p.m. on Friday.
Report Available
3 daysPerforming Laboratory
Mayo Medical Laboratories in Rochester
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 U.S. Food and Drug Administration.CPT Code Information
82657
88184