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Antigens are molecules that evoke an immunological response from the body. Most antigens are proteins but they can be almost
any molecule including carbohydrates, DNA and RNA. Because many proteins are unique to bacterial and virus species, antigens
act like identification tags for unwanted or dangerous invaders and are the means by which the immune system identifies what it
should destroy.
Auto-antigens are antigens in the body's own tissue. Why the immune system targets its own tissue is unclear but it seems to be
the driving force behind autoimmune diseases such as multiple sclerosis.
The acquired immune system is that part of the immune system which learns to recognise and respond to specific viruses, bacteria
and fungi - collectively known as pathogens. The acquired immune system responds to pathogens by binding to small sections of
their broken down proteins. Proteins are made up of small building blocks called amino acids which are directly coded for in the
DNA. The amino acids join together like beads on the string of a necklace to form the proteins. Sections of proteins are known as
peptides or peptide strings. Those peptides which elicit an immune response are known as antigens. The small sections of
antigens that the cells of the acquired immune system binds to are called epitopes.
The acquired immune system can be divided into two parts, cell-mediated and humoral immunity. Both parts of the acquired
immune system work through types of white blood cells (leukocytes) called lymphocytes. Their are two kinds of lymphocytes -
T-cells and B-cells.
Cell mediated immunity works through T-cells, each of which have thousands of identical receptors on its surface known as T-cell
receptors (TCR). Each TCR binds to a sub-section of an antigen called an epitope or antigenic determinant. The T-cells are
presented with antigens through a doughnut-shaped molecule called the major histocompatibility complex (MHC).
MHC comes in two varieties MHC class I and MHC class II. Almost all cells in the human bodies have MHC class I molecules on their
surfaces which present antigens through their "doughnut holes" to a type of T-cell called a killer T-cell. Some specific cells, for
example macrophages, B-cells and dendritic cells have MHC class II molecules on their surfaces. Such cells are called antigen
presenting cells (APC). They present antigens through their holes to another type of T-cell called a helper T-cell.
Humoral immunity works via antibodies which bind to the epitopes on antigens either directly or indirectly through an intermediate
molecule called a hapten. When an antibody binds to an antigen, it may either render it inactive just by being bound to it, or act as
a signal to yet other types of immune system cells, called phagocytes, to engulf (phagocytose) it.
Multiple Sclerosis is thought to be primarily a cell-mediated autoimmune disease operating via helper T-cells which target antigens
in the proteins that make up myelin.
any molecule including carbohydrates, DNA and RNA. Because many proteins are unique to bacterial and virus species, antigens
act like identification tags for unwanted or dangerous invaders and are the means by which the immune system identifies what it
should destroy.
Auto-antigens are antigens in the body's own tissue. Why the immune system targets its own tissue is unclear but it seems to be
the driving force behind autoimmune diseases such as multiple sclerosis.
The acquired immune system is that part of the immune system which learns to recognise and respond to specific viruses, bacteria
and fungi - collectively known as pathogens. The acquired immune system responds to pathogens by binding to small sections of
their broken down proteins. Proteins are made up of small building blocks called amino acids which are directly coded for in the
DNA. The amino acids join together like beads on the string of a necklace to form the proteins. Sections of proteins are known as
peptides or peptide strings. Those peptides which elicit an immune response are known as antigens. The small sections of
antigens that the cells of the acquired immune system binds to are called epitopes.
The acquired immune system can be divided into two parts, cell-mediated and humoral immunity. Both parts of the acquired
immune system work through types of white blood cells (leukocytes) called lymphocytes. Their are two kinds of lymphocytes -
T-cells and B-cells.
Cell mediated immunity works through T-cells, each of which have thousands of identical receptors on its surface known as T-cell
receptors (TCR). Each TCR binds to a sub-section of an antigen called an epitope or antigenic determinant. The T-cells are
presented with antigens through a doughnut-shaped molecule called the major histocompatibility complex (MHC).
MHC comes in two varieties MHC class I and MHC class II. Almost all cells in the human bodies have MHC class I molecules on their
surfaces which present antigens through their "doughnut holes" to a type of T-cell called a killer T-cell. Some specific cells, for
example macrophages, B-cells and dendritic cells have MHC class II molecules on their surfaces. Such cells are called antigen
presenting cells (APC). They present antigens through their holes to another type of T-cell called a helper T-cell.
Humoral immunity works via antibodies which bind to the epitopes on antigens either directly or indirectly through an intermediate
molecule called a hapten. When an antibody binds to an antigen, it may either render it inactive just by being bound to it, or act as
a signal to yet other types of immune system cells, called phagocytes, to engulf (phagocytose) it.
Multiple Sclerosis is thought to be primarily a cell-mediated autoimmune disease operating via helper T-cells which target antigens
in the proteins that make up myelin.
Antibodies are a group of molecules that bind to specific proteins (antigens). Once an antibody is bound with its antigen, it signals to
the rest of the immune system to destroy the cell to which that antigen belongs. Antibodies begin life as receptors on a type of white
blood cell called a B cell. They are shed in vast numbers in a soluble form when the B cell encounters the specific antigen to which its
receptors bind.
the rest of the immune system to destroy the cell to which that antigen belongs. Antibodies begin life as receptors on a type of white
blood cell called a B cell. They are shed in vast numbers in a soluble form when the B cell encounters the specific antigen to which its
receptors bind.
Autoimmunity is when the body's natural defences (the immune system) mistakenly attacks the body's own tissue. "Auto" is derived
from the Greek auto, meaning self, and autoimmune means attacking self.
There are a large number of diseases that are believed to be autoimmune. These include Multiple Sclerosis (MS), Addison's Disease,
Angiitis, Alopecia Areata, Ankylosing Spondylitis, Antiphospholipid Syndrome, Autism, Autoimmune Haemolytic Anaemia, Autoimmune
Hepatitis, Behcet's Syndrome, Berger's disease, Bullous Pemphigoid, Cardiomyopathy, Coeliac Disease, Chronic Fatigue Syndrome
(CFS, CFIDS), Chronic Inflammatory Polyneuropathy, Churg-Strauss Syndrome, CREST Syndrome, Crohn's Disease,
Dermatomyositis, Fibromyalgia, Giant Cell Arteritis, Grave's Disease, Guillain Barre Syndrome, Hashimoto's Thyroiditis, Idiopathic
Pulmonary Fibrosis, Idiopathic Thrombocytopenia Purpura (ITP), Type 1 Diabetes, Lichen Planus, Ménière's Disease, Mixed
Connective Tissue Disease, Myasthenia Gravis, Polyarteritis Nodosa, Polymyalgia Rheumatica, Polymyositis, Primary Biliary Cirrhosis,
Psoriasis, Raynaud's Disease, Reiter's Syndrome, Relapsing Polychondritis, Rheumatic Fever, Rheumatoid Arthritis (RA), Sarcoidosis,
Scleroderma, Sjögren's Syndrome, Stiff-Man Syndrome, Systemic Lupus Erythematosus (SLE), Ulcerative Colitis, Uveitis, Vitiligo and
Wegener's Granulomatosis.
The cause of most autoimmune diseases is unknown but most seem to arise out of a combination of a genetic susceptibility (as
demonstrated by twin and other family studies) and environmental factors, perhaps infection, although no one has a clear idea what
these are. In a few autoimmune diseases, such as System Lupus Erythematosus, a genetic mutation has been identified, although
having this gene does not guarantee that the individual will develop Lupus. Certain genetic mutations to a self-identifing protein, the
Major Histocompatibility Complex (MHC), have been linked to a propensity to develop autoimmune diseases.
Many autoimmune diseases are only guessed to be autoimmune because there appears to be an excess of immune system activity
but no pathogen involved.
Some autoimmune diseases are more common in women than men (Rheumatoid Arthritis and System Lupus Erythematosus), some
are equally common in both sexes (Ulcerative Colitis, Lichen Planus) and some are more common in men than women (Reiter's
Syndrome, Autism). The Relapsing-Remitting and Secondary Progressive forms of Multiple Sclerosis are nearly twice as common in
women than in men but the Primary Progressive form is equally common in men as women.
Some autoimmune diseases are associated with others, for example Vitiligo and Lichen Planus are often found in individuals with
another autoimmune diseases. More recent studies have shown a familial trend across many autoimmune diseases - people with one
autoimmune are more likely to have family members with another one. A syndrome known as Multiple Autoimmune Syndrome (MAS) is
defined as a person having three or more autoimmune diseases.
Hypersensitivity and allergic diseases such as asthma, migraine and eczema are sometimes considered to be autoimmune diseases.
These generally result from an inappropriate immune response to a harmless substance such as pollen. However it appears that the
etiology and pathogenesis of these complaints is quite different to that of the autoimmune diseases.
The immune mechanisms differ from one autoimmune disease to another. In many, including multiple sclerosis, it appears that the
specific immune system (T-cells and B-cells) are targetting protein segments (antigens) derived from the body's own tissue. In MS, it
appears that these antigens are derived from myelin, the insulating sheath to nerve fibres (neurons) in the central nervous system.
from the Greek auto, meaning self, and autoimmune means attacking self.
There are a large number of diseases that are believed to be autoimmune. These include Multiple Sclerosis (MS), Addison's Disease,
Angiitis, Alopecia Areata, Ankylosing Spondylitis, Antiphospholipid Syndrome, Autism, Autoimmune Haemolytic Anaemia, Autoimmune
Hepatitis, Behcet's Syndrome, Berger's disease, Bullous Pemphigoid, Cardiomyopathy, Coeliac Disease, Chronic Fatigue Syndrome
(CFS, CFIDS), Chronic Inflammatory Polyneuropathy, Churg-Strauss Syndrome, CREST Syndrome, Crohn's Disease,
Dermatomyositis, Fibromyalgia, Giant Cell Arteritis, Grave's Disease, Guillain Barre Syndrome, Hashimoto's Thyroiditis, Idiopathic
Pulmonary Fibrosis, Idiopathic Thrombocytopenia Purpura (ITP), Type 1 Diabetes, Lichen Planus, Ménière's Disease, Mixed
Connective Tissue Disease, Myasthenia Gravis, Polyarteritis Nodosa, Polymyalgia Rheumatica, Polymyositis, Primary Biliary Cirrhosis,
Psoriasis, Raynaud's Disease, Reiter's Syndrome, Relapsing Polychondritis, Rheumatic Fever, Rheumatoid Arthritis (RA), Sarcoidosis,
Scleroderma, Sjögren's Syndrome, Stiff-Man Syndrome, Systemic Lupus Erythematosus (SLE), Ulcerative Colitis, Uveitis, Vitiligo and
Wegener's Granulomatosis.
The cause of most autoimmune diseases is unknown but most seem to arise out of a combination of a genetic susceptibility (as
demonstrated by twin and other family studies) and environmental factors, perhaps infection, although no one has a clear idea what
these are. In a few autoimmune diseases, such as System Lupus Erythematosus, a genetic mutation has been identified, although
having this gene does not guarantee that the individual will develop Lupus. Certain genetic mutations to a self-identifing protein, the
Major Histocompatibility Complex (MHC), have been linked to a propensity to develop autoimmune diseases.
Many autoimmune diseases are only guessed to be autoimmune because there appears to be an excess of immune system activity
but no pathogen involved.
Some autoimmune diseases are more common in women than men (Rheumatoid Arthritis and System Lupus Erythematosus), some
are equally common in both sexes (Ulcerative Colitis, Lichen Planus) and some are more common in men than women (Reiter's
Syndrome, Autism). The Relapsing-Remitting and Secondary Progressive forms of Multiple Sclerosis are nearly twice as common in
women than in men but the Primary Progressive form is equally common in men as women.
Some autoimmune diseases are associated with others, for example Vitiligo and Lichen Planus are often found in individuals with
another autoimmune diseases. More recent studies have shown a familial trend across many autoimmune diseases - people with one
autoimmune are more likely to have family members with another one. A syndrome known as Multiple Autoimmune Syndrome (MAS) is
defined as a person having three or more autoimmune diseases.
Hypersensitivity and allergic diseases such as asthma, migraine and eczema are sometimes considered to be autoimmune diseases.
These generally result from an inappropriate immune response to a harmless substance such as pollen. However it appears that the
etiology and pathogenesis of these complaints is quite different to that of the autoimmune diseases.
The immune mechanisms differ from one autoimmune disease to another. In many, including multiple sclerosis, it appears that the
specific immune system (T-cells and B-cells) are targetting protein segments (antigens) derived from the body's own tissue. In MS, it
appears that these antigens are derived from myelin, the insulating sheath to nerve fibres (neurons) in the central nervous system.
Myelin is a collection of lipid fats and proteins that sheaths the long extensions of nerve cells (neurons) called axons. Myelin
considerably increases the speed that nerve signals (impulses) move down the axons. For example, a thin myelinated axon transmits
impulses at anything from 5 to 30 metres per second whereas an unmyelinated one transmits them at 0.5 to 2 meters per second. It
does this both by insulating and containing the nerves.
See this diagram of a neuron which shows how the myelin wraps the axon:
A nerve impulse is a wave of depolarising current called an action potential that travels along the entire neuron by allowing charged
ions of sodium and potassium to flood through channels in the semi-permeable membrane around the nerve cell. At rest (resting
potential), the neuron and the surrounding space act as a "capacitor" storing current which is released during the action potential.
Myelin increases the speed of the transmission by containing the current (as positively charged ions) in a small space surrounding
the axon. This means that the sodium and potassium ions that contribute to the resting potential do not have far to move when the
action potential occurs. Myelin also prevents current from being lost as sodium ions drift away from the neuron.
The myelin sheath is broken at intervals called the nodes of Ranvier which are rich in sodium channels. This makes the nerve
impulses move in a stepwise fashion called "salutatory conduction".
Myelin is composed of about 80% lipid fats and about 20% proteins. Some of the proteins that make up myelin are Myelin Basic
Protein (MBP), Myelin Oligodendrocyte Glycoprotein (MOG) and Proteolipid Protein (PLP).
Myelin occurs in both the Central Nervous System (CNS) and the Peripheral Nervous System (PNS) but the cells that produce the
myelin differ. In the PNS, cells called Schwann cells produce and maintain the myelin whereas, in the CNS, glial cells called
oligodendrocytes produce and maintain the myelin.
In Multiple Sclerosis, the myelin is destructively removed from around the axon which slows down nerve impulses in a process known
as demyelination. In MS, axons are demyelinated in inflammatory patches called lesions. As the disease progresses,
oligodendrocytes and, ultimately, the axons themselves are destroyed. There is very compelling evidence that the destruction is
caused by the body's own immune system i.e. that multiple sclerosis is an autoimmune disease.
Moreover, it is likely that immune response is mediated by a division of the specific immune system called cellular immunity. Cellular
immunity is driven by a type of white blood cell (leukocyte) called a T-cell. These T-cells recognise particular sub-sections of proteins
called antigens. It seems likely from animal models of multiple sclerosis (experimental autoimmune encephalomyelitis) that initial
relapsing-remitting phases of the disease centre on one antigen component, perhaps of myelin basic protein, but that, as the
disease progresses, antigens from other proteins become involved.
considerably increases the speed that nerve signals (impulses) move down the axons. For example, a thin myelinated axon transmits
impulses at anything from 5 to 30 metres per second whereas an unmyelinated one transmits them at 0.5 to 2 meters per second. It
does this both by insulating and containing the nerves.
See this diagram of a neuron which shows how the myelin wraps the axon:
A nerve impulse is a wave of depolarising current called an action potential that travels along the entire neuron by allowing charged
ions of sodium and potassium to flood through channels in the semi-permeable membrane around the nerve cell. At rest (resting
potential), the neuron and the surrounding space act as a "capacitor" storing current which is released during the action potential.
Myelin increases the speed of the transmission by containing the current (as positively charged ions) in a small space surrounding
the axon. This means that the sodium and potassium ions that contribute to the resting potential do not have far to move when the
action potential occurs. Myelin also prevents current from being lost as sodium ions drift away from the neuron.
The myelin sheath is broken at intervals called the nodes of Ranvier which are rich in sodium channels. This makes the nerve
impulses move in a stepwise fashion called "salutatory conduction".
Myelin is composed of about 80% lipid fats and about 20% proteins. Some of the proteins that make up myelin are Myelin Basic
Protein (MBP), Myelin Oligodendrocyte Glycoprotein (MOG) and Proteolipid Protein (PLP).
Myelin occurs in both the Central Nervous System (CNS) and the Peripheral Nervous System (PNS) but the cells that produce the
myelin differ. In the PNS, cells called Schwann cells produce and maintain the myelin whereas, in the CNS, glial cells called
oligodendrocytes produce and maintain the myelin.
In Multiple Sclerosis, the myelin is destructively removed from around the axon which slows down nerve impulses in a process known
as demyelination. In MS, axons are demyelinated in inflammatory patches called lesions. As the disease progresses,
oligodendrocytes and, ultimately, the axons themselves are destroyed. There is very compelling evidence that the destruction is
caused by the body's own immune system i.e. that multiple sclerosis is an autoimmune disease.
Moreover, it is likely that immune response is mediated by a division of the specific immune system called cellular immunity. Cellular
immunity is driven by a type of white blood cell (leukocyte) called a T-cell. These T-cells recognise particular sub-sections of proteins
called antigens. It seems likely from animal models of multiple sclerosis (experimental autoimmune encephalomyelitis) that initial
relapsing-remitting phases of the disease centre on one antigen component, perhaps of myelin basic protein, but that, as the
disease progresses, antigens from other proteins become involved.
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