A 35-year-old woman comes to the office due to trouble seeing out of her right eye. The patient started having blurry vision and pain with eye movement 2 days ago. She has no headache, vertigo, slurred speech, numbness, or weakness. Two years ago, the patient had an episode of double vision that spontaneously resolved after a few weeks. On physical examination, she has an afferent pupillary defect with markedly reduced visual acuity on the right. Funduscopy reveals blurring of the optic disk margins in the right eye. MRI of the brain reveals multiple, ovoid white matter lesions with perpendicular orientation to the lateral ventricles. This patient's condition is most likely caused by an inappropriate immune response directed against which of the following cells?

Question

A 35-year-old woman comes to the office due to trouble seeing out of her right eye.  The patient started having blurry vision and pain with eye movement 2 days ago.  She has no headache, vertigo, slurred speech, numbness, or weakness.  Two years ago, the patient had an episode of double vision that spontaneously resolved after a few weeks.  On physical examination, she has an afferent pupillary defect with markedly reduced visual acuity on the right.  Funduscopy reveals blurring of the optic disk margins in the right eye.  MRI of the brain reveals multiple, ovoid white matter lesions with perpendicular orientation to the lateral ventricles.  This patient's condition is most likely caused by an inappropriate immune response directed against which of the following cells?

Quizplus · Accepted Answer

11ec160b_39d2_a443_9249_af13628ec266_MD0001_00 This patient likely has multiple sclerosis (MS), an autoimmune demyelinating disease of the central nervous system (CNS) that typically presents in young women (age <50) with neurologic deficits (eg, blurry vision, diplopia, focal weakness/numbness, dysarthria, bowel/bladder dysfunction) disseminated in time and space. A common initial manifestation of MS is optic neuritis, characterized by monocular visual loss with pain on eye movement and an afferent pupillary defect. MRI findings in MS typically include white matter lesions scattered throughout the brain and/or spinal cord with a predilection for the subcortical periventricular regions. The pathogenesis of MS involves an autoimmune response targeting oligodendrocytes, the myelin-producing cells of the CNS. Helper T cells abnormally react to antigens in myelin, causing a release of inflammatory cytokines (eg, interferon-gamma) that promote the infiltration of destructive macrophages/microglia and leukocytes. B cells also play a role as most patients with MS have oligoclonal immunoglobulin bands in the cerebrospinal fluid. Myelin degeneration leads to slowed nerve conduction with neurologic deficits as described above. (Choice A) Astrocytes are glial cells (non-neural cells) that contribute to the blood-brain barrier and play an important role in potassium buffering, neurotransmitter metabolism, and glial scar formation. Astrocytes proliferate and form the scar (gliosis) after the attack on oligodendrocytes; astrocytes are usually not targeted by the immunologic response in MS. (Choice B) Ependymal cells are ciliated glial cells that line the ventricles of the brain and the central canal of the spinal cord. They also make up the choroid plexus and produce cerebrospinal fluid. These cells are not targeted by the immune response in MS. (Choice C) Microglia function as the resident macrophages in the CNS. Although they participate in myelin destruction, they are not the target of the immune response in MS. (Choice E) Schwann cells are the myelin-producing cells of the peripheral nervous system. These cells are targeted by the immunologic response associated with peripheral demyelinating disorders (eg, Guillain-Barré syndrome). Educational objective: The pathogenesis of multiple sclerosis involves an autoimmune response (T cell and antibody-mediated) targeting oligodendrocytes and myelin in the central nervous system, leading to slowed nerve conduction with neurologic deficits. __________ References: Immunopathogenesis of multiple sclerosis. (http://www.ncbi.nlm.nih.gov/pubmed/21458377)

A 35-Year-Old Woman Comes to the Office Due to Trouble