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HelpTest Code DHRF Dihydrorhodamine Flow Cytometric N-Formyl-Methionyl-Leucyl-Phenylalanine Test, Blood
Specimen Type
WB Sodium HeparinShipping Instructions
Testing performed Monday through Friday. Specimens not received by 4 p.m. Central time on Fridays may be canceled.
Collect and package specimen as close to shipping time as possible. Ship specimen overnight in an Ambient Shipping Box-Critical Specimens Only (T668) following the instructions in the mailer. It is recommended that specimens arrive within 24 hours of collection.
Specimens arriving on the weekend and observed holidays may be canceled.
Necessary Information
Ordering healthcare professional name and phone number are required.
Specimen Required
Two whole-blood sodium heparin specimens are required, one from the testing patient and the other from an unrelated healthy donor as a control.
Supplies: Ambient Shipping Box-Critical Specimens Only (T668)
Patient:
Container/Tube: Green top (sodium heparin)
Specimen Volume: 5 mL
Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.
Normal Control:
Container/Tube: Green top (sodium heparin)
Specimen Volume: 5 mL
Collection Instructions:
1. Collect a control specimen from the unrelated healthy donor within an hour of the patient's specimen collection time.
2. Clearly label as Normal Control on the outermost label.
3. Send the whole blood specimen in the original tube. Do not aliquot.
4. Rubber band patient specimen and control vial together.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| WB Sodium Heparin | Ambient | 48 hours | GREEN TOP/HEP |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
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 variants in the RAC2 gene, which encodes a Rho family GTPase essential to neutrophil activation and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) function.(1) Patients with Rac2 deficiency have been shown to have normal neutrophil oxidative burst when stimulated with phorbol myristate acetate (PMA), indicating normal NOX 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, is consistent with Rac2 deficiency.(2) By contrast, gain of function variants in RAC2 would lead to an exaggerated response to fMLP.(3)
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 |
fMLP = N-formyl-methionyl-leucyl-phenylalanine
DHR = dihydrorhodamine
MFI = mean fluorescence intensity
The appropriate age-related reference values for Absolute Neutrophil Count will be provided on the report.
Report Available
3 to 4 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
86352
Method Name
Flow Cytometry
Day(s) Performed
Monday through Friday