Allergic response

The allergic response is a hypersensitivity reaction initiated by the immune system in response to exposure to specific substances, termed as allergens. Typically non-harmful, these allergens elicit a robust and often harmful reaction in allergic individuals. The clinical manifestations range from mild symptoms such as sneezing or itching to life-threatening conditions like anaphylaxis.

Depiction of a person suffering from Allergic Rhinitis

Dermatographic urticaria

5. Mediators and treatment in allergic response

Mechanism of Allergic Response

Allergic reactions commence when an individual with a predisposition encounters an allergen. The immune system recognizes this as a threat and produces a specific type of antibody known as Immunoglobulin E (IgE). When exposure to the allergen recurs, it binds to the IgE on certain cells, triggering these cells to release various chemicals, with histamine being the most prominent. These chemicals cause the symptoms of an allergic reaction.

Common Allergens

Allergens can be diverse and originate from various sources:

• Foods: Some individuals are allergic to foods such as peanuts, tree nuts, shellfish, eggs, milk, and gluten.
• Environmental Factors: These include pollen from trees, grasses, and weeds, mold spores, pet dander, and dust mites.
• Insect Stings: Bees, wasps, and hornets are typical culprits.
• Medications: Certain drugs, notably penicillin, can induce allergic reactions.
• Others: Some people may react to chemicals, metals like nickel, or even physical factors like sunlight or cold.

Symptoms of Allergic Responses

The presentation of an allergic response depends on the allergen and the individual. Common symptoms encompass:

• Respiratory Symptoms: Wheezing, coughing, nasal congestion, and shortness of breath.
• Dermal Symptoms: Itching, hives, eczema, and swelling of the face, eyes, or lips.
• Gastrointestinal Symptoms: Nausea, vomiting, diarrhea, and abdominal pain.
• Systemic Symptoms: Anaphylaxis, a severe, potentially fatal systemic reaction that can impair breathing and send the body into shock.

Treatment and Management

Allergic Rhinitis

Allergic Conjunctivitis

Avoidance: The most effective strategy is to identify and avoid allergens. Medications:

• • Antihistamines: These counteract the effects of histamine.
  • Corticosteroids: Often prescribed to reduce inflammation.
  • Decongestants: Provide relief from nasal congestion.
• Allergy Shots (Immunotherapy): Regular injections of the allergen in gradually increasing amounts to desensitize the immune system.
• Emergency Epinephrine: Individuals at risk for anaphylaxis may carry an auto-injector that delivers a dose of epinephrine in emergency situations called Epipen.

Genetic and Environmental Factors

While the exact cause of allergies remains unknown, there's clear evidence that both genetics and environmental exposures play a role. Having family members with allergies can increase one's risk, but it doesn't guarantee an individual will have them. Moreover, exposure to certain infections during childhood, environmental pollution, dietary changes, and the use of antibiotics might influence the development of allergies.

Conclusion

Allergic responses are an intricate interplay of genetic predisposition and environmental exposure. While the triggers and severity may vary, the crux is an overzealous immune system reacting to generally harmless substances. Early identification, proper management, and patient education are crucial to improve quality of life for allergic individuals.

See Also

• Immunology
• Anaphylaxis
• Histamine
• Immunoglobulin E

External links

• Allergic response entry in the public domain NCI Dictionary of Cancer Terms