The whole antibody thing is rather poorly understood. Some get antibodies quickly despite following all of the known guidelines (like starting a biologic concurrently with thiopurines: azathiopurine/imuran/6mp/mtx). Some never get antibodies, despite not following said guidelines.
Let's take a look at the way our immune system is designed to work.
A small, foreign protein first starts circulating within our blood stream, then it is considered to be a virus and the immune system starts building antibody-proteins to try and block it. That initial exposure is a very active phase of the immune system, and a small protein like Remicade looks no different than a virus to our immune system. So starting concurrently remicade and imuran/azathioprine is suspected to reduce the activity of the immune system and slow it's ability to make antibodies. Best practice is to start both at once, and keep on aza for at least 6-months (some discontinue after that).
If the immune system initially fails to create an antibody, then it waits until the next most active phase for a second try. When a virus is defeated by other means (say the body temperature is raised, the virus is ill-adapted to human hosts and unable to reproduce efficiently, and dies out) the immune system recognizes the broken and disabled pieces of the dead virus and begins a second try at producing antibodies to it. Often this second phase is easier, as you have a dead and immobile virus it is contending with. This is usually when you quit a biologic.
That's the laymen's understanding of the current thought process behind antibodies.
TLDR; If you passed the first 6-8 months without getting antibodies then it is unlikely you will.
Generally speaking, we all flare eventually even when we're on strong medications like remicade. Doesn't necessarily mean there's antibody formation that's causing it. You can always get a blood test just before her next scheduled remicade infusion, to check her minimum concentration and antibody levels. Many labs do this, here;s an example: https://www.labcorp.com/test-menu/29496/infliximab-concentration-and-anti-infliximab-antibody
. Often the answer is to increase the frequency and/or dosage of remicade, and that often brings folks back into response. Small levels of antibodies are of little concern and can be overcome with more medicine. In a worst case scenario, you switch to another anti-tnf medication, like humira or simponi and there's enough difference within the chemical structure that your immune system has to start over, from zero and figure out new antibodies to it.
Moderator Ulcerative Colitis
John, 40, UC Proctosigmoiditis
Rx: Remicade @5mgs/kg/6wks; daily 75mgs 6MP, 4.8g generic-Lialda, and rowasaYou never really appreciate what you've got until it's gone. Toilet paper is a good example.