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Most treatments for multiple sclerosis (MS) focus on a type of white blood cell called T cells. But a newer form of treatment focuses on a different form of white blood cell called B cells. They fight infection by creating antibodies, which are blood proteins that trap infections as they try to invade your body.

B cells aren’t usually located in your brain or spinal cord. But if you have MS, they often end up there, where they can cause damage. B cells make antibodies that can attack the myelin that protects your nerves. They also activate T cells that attack myelin. That contributes to MS symptoms.

But B-cell therapy helps change how B cells behave. That can ease MS symptoms and slow the progression of the condition.

How Is B-Cell Therapy Given?

There are three forms of B-cell therapy that doctors prescribe for people with MS.

Ocrelizumab (Ocrevus) is a drug that sticks to B cells and destroys them. That helps prevent MS damage and symptoms. It’s approved by the FDA for:

  • Clinically isolated syndrome
  • Relapsing remitting MS
  • Secondary progressive MS
  • Primary progressive MS

You get ocrelizumab through an infusion into your vein in a doctor’s office or clinic. A treatment takes about 3 hours. You’ll get two doses 2 weeks apart. Then you’ll get one every 6 months.

Your doctor may give you a corticosteroid, an antihistamine, or other medications before your injection to prevent or lessen any reactions to the injection, such as itching or fever.  

Ofatumumab (Kesimpta) is a human-made protein that attaches itself to certain B cells and weakens them so they can’t cause damage.

Ofatumumab is FDA approved for:

  • Clinically isolated syndrome
  • Relapsing remitting MS
  • Secondary progressive MS

Your doctor will teach you how to inject yourself with a syringe at home. Then you or your caregiver will give you the shot. You’ll inject a single dose weekly for 3 weeks, skip a week, and then do one injection each month. 

A third form of B cell therapy, rituximab (Rituxan), hasn’t been approved it as a MS treatment by the FDA. But some doctors may use it “off label” to treat MS. Several clinical trials have shown that rituximab can give you relapses and may slow progression of your MS.

You get the medication through an IV in a doctor’s office. You’ll receive two doses, 2 weeks apart. Then, every 6 months, you’ll get two more doses given 2 weeks apart.


Managing Side Effects

B-cell therapy can cause several side effects. Some of them can be serious. Though the exact side effects for each medication differ, possible issues include:

  • Infection where the needle went in your skin or elsewhere in the body (such as an upper respiratory or urinary tract infection)
  • Allergic reactions to the medication
  • Headache
  • Fatigue
  • Low blood pressure
  • Anemia
  • Slightly higher risk of cancer
  • A weakened immune system

Your doctor will make sure B-cell therapy is right for you. For example, if you have an active hepatitis B infection, you may not be able to get certain types of B-cell therapy until your infection is under control. That’s also true if you’re pregnant or trying to become pregnant.

Your care team will also watch your health while you’re taking the medication to make sure it’s working and to help you deal with side effects. 

© 2023 WebMD, LLC. All rights reserved.

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Mayo Clinic: “Multiple Sclerosis.”

Cleveland Clinic Mellen Center for Multiple Sclerosis: “Mellen Center Approach to Ocrelizumab.”

Multiple Sclerosis Trust (UK): “Ocrevus.”

MS Society (UK): “Targeting B cells to treat progressive MS.”

Fiona Gupta, MD, neurologist and director of wellness and health, Icahn School of Medicine at Mount Sinai, New York City.

National Multiple Sclerosis Society: “FDA Approves Kesimpta® (ofatumumab), Similar to Ocrevus®, for Relapsing MS,” “Ocrevus,” “Non-approved treatments used for MS disease modification.”

Novartis: “Medication Guide: Kesimpta.”

Genenetch: “Medication Guide: Ocrevus.”