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Myelin Oligodendrocyte Glycoprotein (MOG) IgG1 by Flow Cytometry, Serum (1233001248) LAB54825

Johns Hopkins Medical Laboratories announces that the Myelin Oligodendrocyte Glycoprotein (MOG) IgG-1 test can now be performed in-house. The MOG send out test will be discontinued and replaced with the in-house assay.

This advancement will significantly decrease turnaround time and the cost of the test. Providers are advised to order this new in-house MOG test.


Human embryonic kidney cells (HEK293) were grown and transfected with a GFP fusion plasmid to express myelin oligodendrocyte glycoprotein (MOG) variant alpha-1. After resting, the cells are lifted and pre-incubated with Fc receptor binding inhibitors, incubated with diluted patient sera, washed, stained for human IgG1 using a fluorescein-labeled antibody, and then stained for viability using DAPI. The cells are then analyzed using flow cytometry to identify autoantibodies directed against MOG that would support the diagnosis of MOG associated disease (MOGAD) or neuromyelitis optica spectrum disorder (NMOSD).

Specimen Requirements

Testing against transfected HEK293 cells has validated using serum only. Sera may be stored at 2-8ºC for up to 1 month or frozen at -20ºC indefinitely. All frozen samples should be mixed well after thawing and prior to testing.

Hemolyzed samples do not show interference up to 10 g/dL. Icteric specimens do not show interference up to 100 mg/dL. While the presence of triglycerides do not demonstrate interference, lipemic samples should be refrigerated and centrifuged for 5 minutes at 15,000 RPM using the Eppendorf Centrifuge 5424. The serum sample beneath the lipid layer will be analyzed and resulted.

Result Interpretation

The bicistronic plasmid expresses both MOG and a fluorescent GFP construct. High FITC intensity of a cell reflects hyperexpression of MOG, while low FITC intensity reflects no or very little MOG expression. After incubation with patient sera, the cells are washed and incubated with a goat anti-sera recognizing human IgG1 tagged with a fluorescein that can be measured in the APC channel. High APC intensity indicates the presence of many IgG1 antibodies binding to the surface of the HEK293 cells, while low APC intensity indicates no or very little IgG1 reactivity.

  • Qualitative Positive Reaction: autoantibodies against MOG will demonstrate a distinct population in the FITC+ APC+ quadrant.

  • Qualitative Negative Reaction: autoantibodies against MOG will demonstrate no to very few cells in the FITC+ APC+ quadrant, the vast majority of MOG expressing cells will remain in the FITC+ APC- quadrant. Patients with other autoantibodies, as is the case with SLE, may demonstrate reactivity with HEK293 cells regardless of transfection status, so APC positivity may be evident in both FITC- and FITC+ regions equally.

Flow Antibody Index (FAI) calculation:

[(% cells in FITC+ APC+) - (% cells in FITC- APC+)] x [(MFI of FITC+ APC+) / (MFI of FITC- APC-)]

  • Quantitative Positive Reaction: FAI value greater than or equal to 0.3
  • Quantitative Negative Reaction: FAI value less than 0.3

Contact Information

  • Immunology Laboratory - call 410-955-6570