Breaking the rules: The immune system in multiple sclerosis (MS)

Our immune system usually defends and protects the body from invaders. In people with MS, a disease of the central nervous system, the body’s immune system mistakenly attacks the insulation around nerve cells (myelin) in the brain, spinal cord and optic nerves.

The immune cell team in MS¹

A leaky barrier

Most types of immune cells aren't normally found in the nervous system because of the barrier that protects the brain from potentially harmful elements circulating in the blood.

In people with MS, this barrier is compromised – allowing T and B cells to move into the brain and spinal cord.2,3

T cells have long been believed to lead the attack on the nervous system. Scientists now believe that B cells also play an important role in MS.4

The B cell lineup⁵

There are different types of B cells, depending on their stage of development. Each type of B cell has a job to do – from recognizing foreign invaders to making antibodies.

B cells can be distinguished by different combinations of proteins on their surface. Here are a few examples:

  • Purple: CD19

  • Green: CD20

  • Red: CD27

4 moves T and B cells may make in MS

1. B cells recognize myelin and tell T cells to launch an immune attack6,7

2. T and B cells release chemicals that attract other immune cells that cause inflammation8,9

3. B cells make and release antibodies that attack myelin and recruit the help of other immune cells10,11

4. T and B cells establish permanent residence in the central nervous system and continue the attack12,13


  1. Duffy SS, et al. (2014). The contribution of immune and glial cell types in experimental autoimmune encephalomyelitis and multiple sclerosis. Mult Scler Int, 2014:285245.

  2. Ortiz GG, et al. (2014). Role of the blood-brain barrier in multiple sclerosis. Archives of Medical Research, 45:687-697.

  3. Larochelle C. (2011) How do immune cells overcome the blood–brain barrier in multiple sclerosis? FEBS Letters, 585(23):3770-3780.

  4. Cross AH, Waubant E. (2011). MS and the B cell controversy. Biochim Biophys Acta, 1812(2):231-238.

  5. Dalakas MC. (2008). B cells as therapeutic targets in autoimmune neurological disorders. Nature Clinical Practice Neurology, 4(10):557-567.

  6. Constant SL. (1999). B lymphocytes as antigen-presenting cells for CD4+ T cell priming in vivo. J Immunol, 162(10):5695-5703.

  7. Crawford A, et al. (2006). Primary T cell expansion and differentiation in vivo requires antigen presentation by B cells. J Immunol, 176(6):3498-3506.

  8. Bar-Or A, et al. (2010). Abnormal B-cell cytokine responses a trigger of T-cell-mediated disease in MS? Ann Neurol, 67(4):452-461.

  9. Duddy M, et al. (2007). Distinct effector cytokine profiles of memory and naive human B cell subsets and implication in multiple sclerosis. J Immunol, 178(10):6092-6099.

  10. Genain CP, et al. (1999). Identification of autoantibodies associated with myelin damage in multiple sclerosis. Nat Med, 5(2):170-175.

  11. Storch MK, et al. (1998). Multiple sclerosis: in situ evidence for antibody- and complement-mediated demyelination. Ann Neurol, 43(4):465-471.

  12. Serafini B, et al. (2004). Detection of ectopic B-cell follicles with germinal centers in the meninges of patients with secondary progressive multiple sclerosis. Brain Pathol, 14(2):164-174.

  13. Magliozzi R, et al. (2010). A Gradient of neuronal loss and meningeal inflammation in multiple sclerosis. Ann Neurol, 68(4):477-493.


Immune System in MS

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