I don't know anything about the particular antibody that you mentioned. A VGKC antibody in my blood work is what got my cidp diagnosis.
If you look up your insurance company info online it should show a list of conditions that they cover ivig for.
Sometimes you can have a phone hearing with a small panel of people from the ins .co. (a Dr. should always be on the panel) and present your case. They might cover for conditions not on the list. If you get to that point, do your research, try to put that panel in your shoes. Worked for me when I needed rituxin, which isn't typically used for cidp.