Active lesion - Lesion that is new or growing
Adhesion molecule - A protein that promotes the binding of one cell to another or to the extracellular matrix.
Antibody - A protein made by a plasma cell (mature B cell) that protects the body against foreign invaders like bacteria and viruses.
Antigen - A substance that is bound by antibodies. The name ‘antigen’ arises from the ability to generate antibodies. Viral and bacterial molecules and even the body’s own molecules can be antigens.
Angiogenesis - The formation of new blood vessels.
Antigen presenting cell - A specialized cell that sticks pieces of antigen combined with self ‘display’ molecules on its surface for passing immune cells to survey. Dendritic cells, macrophages and B cells are the main antigen-presenting cells.
Astrocyte - A support cell in the central nervous system (CNS) that attaches to both nerve cells and blood vessels; provides metabolic, nutritional and physical support. Astrocytes make the scars on damaged tissue during MS.
B cell - An antibody-making lymphocyte (white blood cell) originating in the bone marrow.
Biological marker (biomarker) - a measurable indicator of a biological process that can be used as a predictor of health or disease. Biomarkers that are being evaluated for MS include those that reflect changes in the immune system, damage to myelin and nerve cells, disruption of the blood brain barrier, or myelin repair.
Blinding - a process in clinical trials that involves concealing information about a test or treatment from the experimenter, subject, or both (double-blind), in order to eliminate potential bias – whether intentional or accidental – from interpretation of the data.
Blood brain barrier (BBB) - A barrier formed by a continuous layer of tightly connected endothelial cells; prevents most large molecules and cells found in the blood from entering the brain tissue.
Brain atrophy- Loss of brain tissue (brain shrinkage)
Central nervous system (CNS) - The brain and the spinal cord; all parts can be affected by multiple sclerosis.
Cerebral spinal fluid (CSF) - The fluid that bathes the surfaces of the central nervous system.
Chemokine - A protein beacon that attracts white blood cells bearing a receptor for the chemokine.
Cytokine - A small messenger molecule that influences the actions of immune system cells; also called a lymphokine or interleukin (IL). There are many different cytokines, each acting only on cells that have receptors for that cytokine.
Demyelination - Process during which myelin is stripped from nerve fibres.
Dendritic cells – A white blood cell that is bone-marrow derived and specializes in presenting antigen to T cells.
Differentiation - A series of steps that cells go through to reach their mature state.
Deoxyribonucleic acid (DNA) - The code of genetic instructions that shapes the development of every individual. DNA is shaped as a double helix and is made up of nucleic acid-sugar complexes loosely bound to proteins.
Expanded Disability Status Score (EDSS) - A test for measuring the disability level of a person with MS; also known as the Kurtkze Scale after, Dr. John Kurtzke.
Endothelial cell - Lines the heart and blood vessels of the circulatory and immune systems; forms the blood brain barrier (BBB).
Experimental autoimmune encephalomyelitis (EAE) - An MS-like disease created in laboratory mice after they are injected with CNS tissue or a derivative of myelin basic protein.
Functional magnetic resonance imaging (fMRI) - An imaging technique that looks at blood flow in the brain in real time to detect areas of activity. Where there is increased activity, blood flow to that region increases.
Gadolinium enhanced lesion (GEL) - Gadolinium is a chemical compound used to visualize tissue on MRI scans which are affected by inflammation. Gadolinium cannot normally pass enter the brain because it is a
large molecule, but when there is active inflammation the barrier which separates the circulating blood and brain is ‘leaky’ and gadolinium can get through. Thus, gadolinium makes it possible to identify new or growing lesions.
Gene - Pieces of DNA that include the genetic code for making body proteins; located on chromosomes.
Glial cell – Support cells in the nervous system; oligodendrocytes, astrocytes and microglial cells in the central nervous system and Schwann cells in the peripheral nervous system.
Health Related Quality of Life (HRQL) - Quality of life of people with MS based on patient-perceived functional status and well-being.
Immunoglobulin - The membrane-bound version of antibody that binds antigens and signals the B cell to secrete antibodies.
Immunoregulation - The control of specific responses in the immune system.
Inflammation – Normally protective response to physical/chemical injury, infection or a local immune response leading to tissue damage where loss of function may accompany swelling, redness, heat and pain; fluid, white blood cells and plasma proteins accumulate.
Interferons (IFN) - Cytokines that help cells to fight viruses. Alpha interferon and beta interferon are made by white blood cells, fibroblasts and other cells. (Manufactured versions are useful as MS treatments.) Gamma interferon is produced by inflammatory T cells and natural killer cells and its main action is to trigger macrophages to help fight infection. Gamma interferon makes MS worse.
Lesion - A wound to body tissues. In MS, a lesion which occurs in myelin of the central nervous system is called a plaque. See plaque.
Lipid - Fat soluble. A term describing the ability of molecules, such as fats, fatty acids and soaps, to dissolve in fat.
Lymphocytes - White blood cells (B cells, T cells and NK cells) of the immune system that fight specific infections.
Macrophage - An immune cell that is among the first line of defence against invaders; also acts as antigen presenting cells. Macrophages are called different names depending where they are found in the body (e.g. microglial cells in the brain).
Magnetic resonance imaging (MRI) - A technological tool that detects energy released from hydrogen atoms to create anatomical images. MR images of soft tissues of the body including the brain and spinal cord clearly show MS lesions and may be used to track disease progress.
Magnetic resonance spectroscopy (MRS) - A technological tool similar to magnetic resonance imaging but providing chemical rather than anatomical information. MRS is most useful when evaluating trials of new treatments by measuring disease severity and progression.
Mass Spectrometry - A technique used to measure the mass of molecules or group of molecules.
Mast cell - Originates in the bone marrow; involved in allergic responses.
Memory B cells - B cells living in the body for long periods of time; can be triggered to make antibodies.
Microglia - Macrophage-like cells that reside in the brain; ‘eat’ cellular debris and stimulate immune responses.
Monocyte - A white blood cell that resides only in the blood. Once it migrates into the tissues, a monocyte is called a macrophage.
Morphogen - Diffusable substance that influences movement and organization of cells during development.
MSQLI - The Multiple Sclerosis Quality of Life Inventory is a questionnaire designed to evaluate the burden of disease experienced by people with MS.
Myelin basic protein (MBP) - One of the principal proteins found in myelin.
Myelin - A collection of proteins and lipids that make up the myelin sheath; speeds transmission of signals along nerve fibres.
Myelin is made by cells in the central nervous system called oligodendrocytes. These cells wrap themselves around nerve axons very many times to form a protective myelin sheath. The myelin increases the speed at which nerve signals travel along axons. In MS, myelin is vulnerable to attack from the immune system.
Myelin sheath - 1-200 insulating layers of myelin surrounding nerve fibres in the central and peripheral nervous system.
Nerve fibre (axon) - The slender, long branch extending from a nerve cell that carries nerve impulses to adjacent nerve cells throughout the body. Most nerve fibres are surrounded by 1-200 layers of myelin.
Neurodegeneration - Degeneration and death of
Neuroglia (glial cells) - Supporting, non-impulse generating cells of the nervous system (e.g. astrocytes and oligodendrocytes).
Neuron - A cell within the nervous system that consists of a cell body and the associated membrane extensions, called dendrites when highly branched, or axons when minimally branched. Nerve impulses travel along nerve axons.
Neuroprotection – The preservation of the structural and functional integrity of nerve cells
Neutrophil - A type of white blood cell that migrates quickly to a site of inflammation to help fight infections
NK cells - Natural Killer cells are a group of lymphocytes (not T or B cells) that can kill some virally infected and tumor cells.
No evidence of disease activity (NEDA) – a new criterion for assessing the effectiveness of a treatment for MS on the basis of complete remission across four key disease measures: relapses, MRI lesions, brain volume loss, and disability progression. NEDA represents a shift in treatment expectations with the introduction of new, more effective drugs, although more research is needed before it can become widely adopted.
Oligodendrocyte - The cell in the CNS that makes and maintains myelin; wraps its myelin-filled membranes around nerve fibres (axons).
Oligodendrocyte precursor cell (OPC) - Younger version of oligodendrocytes
Peptide - A chain of amino acid building blocks strung together. The chain can be two (di-) amino acids, three (tri-) amino acids, or more (poly-) amino acids in length.
Peripheral nervous system (PNS) - Nervous system in the body aside from the brain and spinal cord. The PNS can be affected by MS.
Placebo - a substance used in clinical trials to resemble an actual treatment or medicine (i.e. a dummy or mock treatment). Use of a placebo can help determine how much benefit is being derived from the actual treatment, and how much is due to the psychological state of the subject (i.e. placebo effect).
Plaque - An area of myelin loss characteristic of multiple sclerosis.
Proteolipid Protein (PLP) - One of the major proteins found in the myelin sheath.
Randomization - the process whereby participants in a study are randomly assigned to different treatment groups in order to eliminate or reduce bias in any particular group.
Remyelination - Process during which myelin is re-added to nerve fibres by oligodendrocytes or Schwann cells.
Schwann cell - The cell in the peripheral nervous system that makes and maintains myelin.
Stem cell - Unspecialized cell that mature into a cell that performs a highly specific function. Stem cell can also divide to produce more stem cells.
T cell - Immune cells that fight infections. Two broad categories are alpha-beta and gamma-delta T cells. Alpha-beta subsets include helper T cells (CD4+) and killer T cells (CD8+).
T cell receptor (TCR) - A protein found on the surface of T cells. Alpha-beta TCR binds to bits of foreign peptides (or sometimes body peptides, like myelin) attached to cell surface ‘display’ proteins on antigen presenting cells.
Tumor necrosis factor (TNF) - TNF alpha and TNF beta; cytokine made by macrophages and some T cells; toxic to tumor cells; plays role in inflammatory responses.
Transgenic mice - Mice that contain genes from another source (animal or human); derives from ‘trans’ (other) and ‘genic’ (genes).