Multiple sclerosis (MS) is a chronic autoimmune disease in which the body's own immune system mistakenly attacks and degrades the myelin sheath, the protective covering of nerve fibres in the central nervous system.
Explain two distinct methods by which white blood cells defend the human body against invading pathogenic microorganisms.
Suggest two reasons why it is particularly difficult to develop a medical treatment that halts the immune destruction of the myelin sheath without causing other severe, life-threatening health complications.