Final Paper: Immunology 414
4/29/13
Specific Immunological Disease
A rare autoimmune disorder by the name of “neuromyelitis optica” (NMO) causes a
chronic disease called optic neuritis. Individuals who develop the disease often experience pain
in the eyes, and degeneration of vision. Transverse myelitis, an inflammatory symptom of the
spinal cord causing demyelination of the axons, can cause weakness, numbness, and sometimes
paralysis of the arms and legs, along with sensory disturbances and loss of bladder and bowel
control. In general, the autoimmune system of individual malfunctions due to processes that are
not completely understood, and antibodies and other targeting cells attack and destroy
myelinated cells in the spinal cord and optic nerves.
Before much was known of NMO’s pathology, it was diagnosed in patients experiencing
a rapid onset of blindness or severe degeneration of vision accompanied by loss of feeling in the
extremities. This acute paralysis in the arms and legs follows loss of vision, but is more directly
related to the aforementioned secondary process of transverse myelitis, which affects the spinal
cord and brainstem. Episodes of paralysis continue from the beginning of the first attack in a
relatively random and unpredictable manner. Sometimes a sufferer will go a week without an
attack, sometimes years. Most of the time, however, the episodes occur in clusters around a
certain period of time such as monthly, or bimonthly. Prevalence of the onset of NMO is
confined to two life stages: early childhood, and adults in their 40’s, with the disease affecting
women 4 times more than men.
Recent discoveries of the disease’s etiology have brought its singular characteristics to
light. Formerly, it was thought that NMO was more severe variant of multiple sclerosis, a
similar disease that can cause episodes of optic neuritis and myelitis. The current understanding
of NMO separates it from MS in the severity of the attacks and the relatively specifically
associated symptoms (such as uncontrollable vomiting and hiccups due to malfunction of axonal
propagation in the brainstem). In terms of the general etiology and pathology, the direct cause of
NMO is not fully understood, but the method by which it affects the patient’s cells is fairly well-
documented.
The autoimmune system of the individual suffering from NMO targets and attacks “self-
cells.” Specifically an autoantibody termed ‘NMO-IgG’ recognizes aquaporin-4 (AQP4)—a
water channel expressed in astrocytes throughout the central nervous system—as a foreign
antigen and triggers complement dependent cytotoxicity (CDC) and antibody dependent cell-
mediated cytotoxicity. NMO-IgG is considered pathogenic in humans and is prevalent in
