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HelpTest Code LAGGN Granulocyte Antibody Screen, Serum
Specimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Red top (serum gel/SST are not acceptable)
Submission Container/Tube: Plastic vial
Specimen Volume: 1.5 mL Serum
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Additional Information: Only a specimen collected before a transfusion reaction is acceptable.
Useful For
Work-up of individuals with autoimmune neutropenia
Work-up of individuals having febrile nonhemolytic transfusion reactions
Work-up for alloimmune neonatal neutropenia
This test is not useful for the diagnosis of neutropenia due to marrow suppression by drugs or tumors.
Method Name
Flow Cytometry/Agglutination
Reporting Name
Granulocyte Ab Screen, SSpecimen Type
Serum RedSpecimen Minimum Volume
Serum: 0.3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum Red | Refrigerated (preferred) | 30 days |
| Frozen | 365 days | |
| Ambient | 7 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | OK |
Clinical Information
Granulocyte antibodies are induced by pregnancy, prior transfusion, or transplants. These antibodies can cause neutropenia in various autoimmune disorders. Febrile nonhemolytic transfusion reactions and alloimmune neonatal neutropenia may also be caused by granulocyte associated antibodies, including anti-human leukocyte antigen antibodies.
Reference Values
Not applicable
Interpretation
A screening result is considered positive when reactivity is detected by either method. A positive result indicates the presence of granulocyte-reactive antibodies but does not, by itself, establish HNA antibody specificity.
A positive result can be due to anti-granulocyte antibodies and anti-human leukocyte antigen antibodies.
This test cannot distinguish between allo- or autoantibodies, nor can it determine the specificity of the detected antibody. Results should be correlated to clinical history.
Cautions
Testing for patients who receive human monoclonal antibodies like daratumumab may cause false-positive results due to interfering substances. Hemolytic samples have the potential for causing false-positivity and will, therefore, be rejected.
Method Description
Granulocyte antibody screening is performed using two complementary methods in parallel: the granulocyte immunofluorescence test (GIFT) and the granulocyte agglutination test (GAT).
For both methods, patient serum is incubated with freshly isolated granulocytes from a healthy donor.
In the GIFT method, IgG- and IgM-class antibodies in patient serum that bind to donor granulocytes are detected using fluorescently labeled anti-human immunoglobulin reagents. Samples are analyzed by flow cytometry, and IgG and IgM reactivity are evaluated by comparison with appropriate negative controls.
In the GAT method, antibodies that cause donor granulocytes to agglutinate are detected by bright-field microscopy. Agglutination is assessed based on the extent of cell aggregation observed.(Fung YL, Minchinton RM. The fundamentals of neutrophil antigen and antibody investigations. ISBT Science Series. 2011;6:381-386)
Day(s) Performed
Tuesday, Thursday
Report Available
7 to 15 daysSpecimen Retention Time
7 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
86021 x2
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| LAGGN | Granulocyte Ab Screen, S | 105285-1 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| LAGG2 | GIFT/GAT Interpretation | 105288-5 |
| LAGG3 | GIFT Result | 105286-9 |
| LAGG4 | GAT Result | 105287-7 |