Allergy and Hypersensitivity Reactions - Class XII

Hay fever or allergic rhinitis is the allergic response caused by the hypersensitivity of dust, mites, animal fur or hairs. It is characterized by the running nose, sneezing and watery, itchy eyes. Whereas enteric fever is caused by the bacteria, Skin cancer is caused by harmful radiation i.e., UV rays and Goiter is the metabolic disorder. Thus, the correct answer is option B.

A- Anaphylaxis is a rapid, severe and generalized allergic reaction which may lead to death. Prompt administration of epinephrine injection can be life-saving. Timely administration of epinephrine injection decreases hospitalizations and mortality. 

Histamines are the inflammatory substances which are released by the mast cells and basophils during the allergic reactions. The excessive release of histamine may result in anaphylactic shock. Anaphylaxis is a type of severe allergic reaction which can result in the death of the person. Antihistamines are used for the treatment and cure of the allergic reactions.

Anaphylaxis is a type of severe allergic reaction which can result in the death of the person. The first or the primary treatment which is provided, is that the person is injected with epinephrine which reduces the basic symptoms. Antihistamines are used for the treatment and cure of the allergic reactions. The antihistamines are molecules which are similar in structure to histamine and block the H1 receptors which prevent the release and action of histamines. 

Type II hypersensitivity involves antibodies (IgG or IgM) binding to antigens on cell surfaces, leading to complement activation or phagocytosis.

A patch test is used to diagnose contact dermatitis, which is a classic example of Type IV (delayed-type) hypersensitivity.

Type II hypersensitivity is characterized by cytotoxic reactions where antibodies bind to antigens on the cell surface.

Delayed-type hypersensitivity (Type IV) is cell-mediated and includes responses like the Tuberculin skin test and contact dermatitis.

IgE antibodies are called cytotropic because they have a high affinity for receptors on the surface of mast cells and basophils.

In Type II hypersensitivity, antibodies bind to the cell surface (a), which then activates the complement cascade (c), leading to opsonization and phagocytosis (b), and finally cell death (d).

Robert Koch discovered the tuberculin reaction while studying Mycobacterium tuberculosis.

Type IV hypersensitivity is cell-mediated (T-cells) and does not involve antibody-mediated phagocytosis or classical antigen presentation in the same way as humoral responses.

Type IV hypersensitivity is cell-mediated by T-lymphocytes and does not involve antibodies, unlike Types I, II, and III.

The T helper cells also known as CD$ _4^+$ release cytokines and trigger the activity of other immune cells.

In Type IV hypersensitivity, sensitized T-helper cells (specifically Th1 cells) are the first to arrive at the site and release lymphokines to recruit other cells.

The skin prick test works by introducing an allergen into the skin, which triggers an inflammatory reaction (wheal and flare) mediated by IgE on mast cells.

Bronchial asthma is a classic allergic disease characterized by airway inflammation and hypersensitivity to triggers.

The skin prick test is a standard diagnostic procedure used to identify specific allergens causing IgE-mediated allergic reactions.

Anaphylaxis is a severe, life-threatening systemic allergic reaction that affects the entire body. Symptoms often include gastrointestinal distress like nausea, vomiting, and abdominal pain, along with respiratory and cardiovascular symptoms.

Anaphylaxis, also known as anaphylactic shock is a serious allergic reaction that is rapid in onset and may cause death. It typically causes an itchy rash, throat or tongue swelling, shortness of breath, vomiting, lightheadedness, and low blood pressure. Common causes include insect bites and stings, foods, and medications.  The mechanism involves the release of mediators from certain types of white blood cells triggered by either immunologic or non-immunologic mechanisms.

Histamine causes a skin response. If you dont react to histamine, your allergy skin test may not reveal the allergy.

Allergy blood tests, such as those measuring IgE levels, are used to assess the concentration of specific antibodies, identify potential cross-reactivity between allergens, and monitor the development or progression of allergic diseases.

Hay fever, or allergic rhinitis, is primarily triggered by the inhalation of wind-borne pollen grains from trees, grasses, and weeds, which are lightweight and easily dispersed.

Hypersensitivity refers to undesirable reactions produced by the immune system including allergies and autoimmunity. They are usually referred to as an abnormal (aberrant) functioning of the immune system and these reactions may be damaging, uncomfortable, or occasionally fatal. Hence, hypersensitivity to an allergen is due to the aberrant functioning of the immune system.

Asthma is a chronic inflammation of respiratory tracts due to accumulation of immune cells to destroy dust particles or allergens. Yellow eyes occur in jaundice patient. Jaundice is hepatic disease. Mumps is a contagious disease caused by a virus that primarily effects salivary gland. Typhoid is a bacterial infection caused by Salmonella typhi. So, the correct answer is 'Asthma'.

A mast cell is a type of white blood cell that contains many granules rich in histamine and heparin. Specifically, it is a type of granulocyte derived from the myeloid stem cell that is a part of the immune and neuroimmune systems. Mast cells are primarily known for their role in allergy and anaphylaxis (shock). Mast cells play a key role in the inflammatory process. When activated, a mast cell can either selectively release mediators or compounds that induce inflammation, from storage granules into the local site.

• Anaphylaxis or anaphylactic shock is a serious allergic reaction that is rapid in onset and may cause death. It causes an itchy rash, throat or tongue swelling, shortness of breath, vomiting, lightheadedness, and low blood pressure. These symptoms are seen within minutes to hours. Common causes include insect bites and stings, foods, and medications. The primary treatment of anaphylaxis is epinephrine injection into a muscle, intravenous fluids, and positioning the person flat.
  
• A person stung with the bee is administered penicillin. The person died because insect stings and medication (penicillin) are the major causes of anaphylactic shock and death.

Allergic rhinitis, also known as hay fever is a type of inflammation in the nose which occurs when the immune system hypersensitizes to allergens in the air. Symptoms include a runny or stuffy nose, sneezing, red, itchy, and watery eyes, and swelling around the eyes. Allergic rhinitis is typically triggered by environmental allergens such as pollen, pet hair, dust.

Histamine is an organic nitrogenous compound involved in the inflammatory response and has a central role as a mediator of itching. Histamine causes vasodilation of peripheral blood vessels due to which there is increased blood flow to the site of inflammation. It mediates the inflammatory reaction by the release of other chemical mediators of inflammation and causes redness, swelling etc at the site of inflammation.

In localized infection, redness and heat are due to increased blood flow at body core temperature to the inflamed site, swelling is caused by accumulation of fluid, pain is due to the release of chemicals such as prostaglandin and histamine that stimulate nerve endings.Histamine are mono-amine produced from mast cells and basophils these are stored in preformed granules, and is released to a number of stimuli these lead to arterial dilation and increased venous permeability. Prostaglandins are eicosaniod produced from mast cells they leads to vasodilation, fever and pain. Hence, localized inflammatory response at the sight of infection producing redness, swelling, pain and heat is due to prostaglandin and histamine.

Histamine is an organic nitrogenous compound involved in the inflammatory response and has a central role as a mediator of itching. Histamine is produced by basophils and by mast cells found in nearby connective tissues. Histamine is stored in cytoplasmic granules along with other amines and rapidly released upon triggering with a variety of stimuli. It causes the contraction of smooth muscle, dilation of blood vessels etc..

Immune complex-mediated hypersensitivity (Type III) involves the deposition of antigen-antibody complexes. These complexes are typically cleared from circulation by phagocytic cells, specifically monocytes and eosinophils, which help mitigate tissue damage.

A mast cell is a type of white blood cell that contains many granules rich in histamine and heparin. Mast cells play an important protective role in inflammatory and allergic reactions. When mast cells are activated, they release mediators or compounds that induce inflammation from storage granules into the local site and promotes the inflammatory response. In allergic reactions, mast cells remain inactive until an allergen binds to IgE already coated upon the cell.

• Asthma is a common long-term inflammatory disease of the airways of the lungs.
• Symptoms include reversible airflow obstruction and easily triggered bronchospasms. 
• Symptoms include episodes of wheezing, coughing, chest tightness, and shortness of breath. 
• Asthma can be caused by Environmental factors including allergens, air pollution, and other environmental chemicals.
•  Hence, Asthma is caused by an allergy.
• So, the correct answer is 'Asthma'.

• Shock is a life-threatening situation due to poor tissue perfusion with impaired cellular metabolism, manifested inturns by serious physiological abnormalities.
  
• Anaphylactic shock is also called as Type I immunogenic reaction.
• Anaphylactic shock is characterized High permeability of capillaries causing loss of fluid from the blood.
  
• Anaphylaxis symptoms usually occur within minutes of exposure to an allergen. 
  
• The most common anaphylactic reactions are to foods, insect stings, medications and latex.
  
• So, the correct answer is 'High permeability of capillaries causing loss of fluid from the blood'

Allergies, also known as allergic diseases are caused by hypersensitivity of the immune system to typically harmless substances in the environment. The mechanism involves immunoglobulin E antibodies (IgE) binds to an allergen and then to a receptor on mast cells or basophils where it triggers the release of inflammatory chemicals such as histamine. The release of histamine develops symptoms such as red eyes, an itchy rash, sneezing, a runny nose, shortness of breath, or swelling.

Hay fever (allergic rhinitis) is caused by grass pollen mostly but it can also be caused by tree pollen or weed pollen. Pollen is a fine powder enriched in protein released by plants as part of their reproductive cycle which can cause irritation in nose, eyes and throat. Symptoms of hay fever include sneezing, runny nose, itchy eyes etc. It is more common in spring and early fall. Hepatitis and dengue are viral diseases. Helper T-cells are immunity providing cells in the body

Pollens are present in air. Excess of pollen are produced in certain seasons which causes allergic reactions in several human beings. The common allergic reactions are asthma, bronchitis and rhinitis.

The term anaphylaxis was coined by Charles Richet and Paul Portier in 1902 during their experiments on the effects of sea anemone toxin in dogs.

Hay fever and asthma are the allergic reactions of the body to allergens. Allergy is the hypersensitivity of a person to some foreign substance coming in contact with the body.