Anti Interferon Gamma Antibody (Sendout)

Test Use: Increased susceptibility to BCG or nontuberculous mycobacteria (NTM) may be caused by genetic defects that affect the IL-12 and IFN-gamma pathways. These cytokines are critical to control mycobacterial infections, and disruption of these pathways may lead to severe infections in otherwise healthy individuals. Antibodies to IFN-gamma have been found to result in an acquired form of immunodeficiency that presents as chronic, often extra-pulmonary, infection with NTM.¹ Confirmation of the presence of these autoantibodies may assist with treatment decisions regarding the use of immunomodulation in addition to standard anti-mycobacterial therapy.

Test Algorithm: Anti-IFN-gamma autoantibodies are detected by an initial screening ELISA. If the result is positive, the test reflexes to a flow cytometry assay to determine the ability of the autoantibody to neutralize IFN-gamma by the analysis of IFN-gamma induced phosphorylation of STAT1, a signaling molecule downstream of the IFN-gamma receptor.

Enzyme-linked Immunosorbent Assay (ELISA)

Reflex confirmation, if performed: Flow Cytometry

Outside Laboratories: Allow sample to clot at room temperature for 20 to 60 minutes. Centrifuge specimen and transfer serum to a separate plastic vial. Freeze serum at -70°C while awaiting shipment. Transport samples on dry ice.

Stability: Frozen (-70°C): 1 month; Refrigerated: 48 hours; Ambient: Unacceptable.

Unacceptable Conditions: Clotted or hemolyzed samples, plasma.

Allow sample to clot at room temperature for 20 to 60 minutes. Centrifuge specimen and transfer 1 mL serum each into two separate plastic vials. If sample volume is insufficient, prioritize the sendout test.

• RIFNGA: Store in -70°C/Superfreeze Sendout rack 93.
• UW436: Store in -70°C/Superfreeze Immunology rack 44.

Sendouts:

• Order NJH Test: IFNGE
  • On the NJH Complement/Cytokines requisition under category 7, "Anti-Cytokine Autoantibodies," select IFNGE/Autoantibodies to interferon gamma.
• Ship Monday through Thursday via FedEx Priority Overnight. Include sufficient dry ice to keep the sample frozen until arrival.
• Do not ship on Fridays.

Stability: Frozen (-70°C): 1 month; Refrigerated: 48 hours; Ambient: Unacceptable.

Unacceptable Conditions: Clotted or hemolyzed samples, plasma.