The human body is equipped with a powerful immune system to protect from harmful substances. The purpose of the immune system is not confined strictly to setting a fight against an invader. It keeps a memory of the invader after a successful recognition. There are some breaches where the immune system attacks unexpected components. When an individual's immune system attacks common substances that are harmless to fellow individuals it is termed an Allergy. Autoimmunity is the condition where an individual's immune system mistakenly attacks the self cells and tissues.
Allergy is the body's reaction to typical harmless entities of the environment which pose no harm to most individuals. The substances causing allergies are called allergens.
Humans live in continuous interaction with the environment and are exposed to pollen, dust mites, animal fur, molds, insect venom, and foods. While many individuals remain normal in their course of life, some individuals develop certain adverse symptoms upon exposure to specific substances.
An allergic response can be,
mild and localized to a specific body part that is exposed to an allergen.
Moderate if it is spread to nearby body parts.
Severe if a sudden and life-threatening condition arises.
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An allergy can have a number of responses based on allergen and site of exposure, of which a few common ones are listed below.
Itching, red and swollen eyes.
Sneezing, and watery nose,
Skin rashes or hives.
Swelling of mouth and lips,
Itching oral areas,
Constant cough.
Difficulty in breathing.
Tightness in the chest,
Nausea and vomiting.
Diarrhoea.
Anaphylaxis is a sudden emergency arising from irritation in the eyes to severe swelling of the throat leading to problems in breathing and swallowing. Some people experience dizziness in anaphylactic attack due to a sudden drop in blood pressure.
Autoimmunity is the immune response against self, healthy cells leading to organ destruction or malfunction with major physiological changes.
The human body is equipped with an immune system that evokes an immune response against any foreign substances (antigen) with probable disease-causing abilities. It is carried by white blood cells that directly attack antigen or indirectly produce antibodies against the antigen.
The autoimmune individuals produce autoantibodies against self-antigens or autoantigens leading to the destruction of healthy tissues and organs.
An autoimmune disease is a condition where an individual's immune system produces autoantibodies against self-antigens.
The causes are not exactly known but genetic factors, environmental conditions are studied as contributory factors in some diseases.
Diseases caused by autoimmunity are classified into two types based on the sites experiencing the autoimmune attack.
Organ-specific autoimmune diseases
As the name suggests, only a specific organ or tissue associated with self-antigens is targeted by the immune system, and autoantibodies are directed against the specific organ.
The pathophysiology is concerned with a single organ only.
Some examples are.
Grave’s disease and Hashimoto’s disease are associated with the thyroid gland resulting in its malfunctioning.
Type1 Diabetes patients face low insulin levels because of damage associated with beta cells of the pancreas.
Vitiligo is a skin-specific autoimmune disease, where individuals experience white patches on the skin since the pigmenting melanocytes are the target cells for autoantibodies.
Addison's disease is caused when the adrenal cortex is targeted by the immune system.
The systemic autoimmune effects are widespread with multiple tissue damages to cells belonging to many organs.
The pathophysiology is concerned with a single organ only.
Some examples are.
Systemic lupus erythematosus, where the patients experience inflammation, tissue damage, and fatigue in joints, kidneys, brain, lungs, skin, and blood vessels.
Rheumatoid arthritis is the damage associated with the membrane lining the joints of elbows, shoulders, knees, and hips.
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Although both allergy and autoimmune disease are immune responses with similar general symptoms, there are pretty many differences between them.
The targetted substances are of external origin in Allergies while the targets are of self origin in autoimmune diseases.
Autoimmune diseases end up in tissue destruction or malfunctioning which is not observed in allergic cases.
The mechanism running behind is entirely different between both of them.
Allergen binds to IgE (immunoglobulin E) and activation of mast cells and basophils occurs. It leads to the degranulation of histamines, and cytokines which further carries the biochemical processes for the physical manifestation of allergy. It includes mucus secretion, nerve stimulation, and vasodilation that are manifested through redness, itching, hives, etc. .
Autoimmune diseases start in a separate manner where the immune system mistakes its self cells to be foreign and synthesizes autoantibodies against them.
Autoimmune disease symptoms vary with organ specificity impacting the functioning and physiology related to the organ. The general symptoms of autoimmunity are listed below.
Fatigue.
Muscle pain.
Joint pain and swelling.
Mild recurring fever.
Skin rashes.
Numbness in hands and legs.
Humans are gifted with an efficient immune system that can identify potentially harmful substances and remove them from the body. The fight is not confined to removal itself but it prepares the body efficient enough to face a repeated attack by making a memory of the harmful invader.
Allergy and autoimmune diseases can be considered breaches in the efficiency of the immune system. Allergic individuals evoke an immune response to the common substances which are accepted by most other individuals. Autoimmune disease occurs when the body attacks self-tissues and organs mistaking them for foreign bodies. Both of them follow different mechanisms and are entirely different in diagnosis although some minor symptoms may be the same.
Q1. How are allergies treated?
Ans. Allergies are treated by using antihistamine drugs. Histamines released in an allergic reaction cause the swelling of the skin, and vasodilation which are noted symptoms of allergy. Antihistamine drugs stop histamine binding to the target thereby stopping its effects.
Q2. How is an allergy diagnosed?
Ans. Allergy is diagnosed by performing a skin test and blood test.
A skin prick test is done by placing a drop of allergen on the skin and pricking slightly. A blood test measures the IgE antibodies as a whole for a particular antigen.
Q3. Can allergy lead to death?
Ans. Sometimes allergy leads to sudden and severe reactions which cause death in 15 minutes if remains untreated. Swelling of the throat causing difficulty in breathing, accompanied by a fall in blood pressure is called anaphylactic attack and can lead to death.
Q4. How are autoimmune diseases treated?
Ans. Treatment of autoimmune diseases is aimed at slowing down the immune response along with reducing inflammation and pain. Corticosteroids, anti-inflammatory drugs for inflammation, pain killers for pain, and immunosuppressants to reduce the immune response are a part of the treatment of autoimmune diseases.
Q5. What do immunosuppressants do in patients with autoimmune diseases?
Ans. Patients suffering from the autoimmune disease have an overreacting immune system eliciting an immune response against self-tissues. Immunosuppressants reduce the immune reaction in the body however with side effects like increased incidence of infections.
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