Allergic Rhinitis - causes, symptoms, diagnosis, treatment, pathology

Summary

Allergic rhinitis, also known as hay fever, is a type 1 hypersensitivity reaction triggered by airborne allergens such as pollen, dust, animal hair, or mold spores. The immune system overreacts, leading to inflammation in the eyes and nose, causing symptoms like nasal congestion, itchy eyes, and sneezing. Mast cells release histamine, which dilates blood vessels and increases fluid in the tissues. Diagnosis often involves skin tests, though avoidance of triggers is the primary treatment. Medications like antihistamines and nasal irrigation can help, and desensitization therapies may also reduce symptoms over time.

Takeaways

• 😀 Allergic rhinitis is nasal inflammation commonly triggered by allergens such as pollen, dust, animal hair, and mold spores.
• 😀 The condition is often referred to as hay fever, especially during specific times of the year when pollens are prevalent.
• 😀 Allergic rhinitis is a type 1 hypersensitivity reaction involving an imbalance of T-cells, which causes overproduction of IgE antibodies.
• 😀 When pollen enters the nose, it is processed by dendritic cells, which present it to T-cells that, once activated, trigger an immune response.
• 😀 Activated T-cells stimulate B-cells to produce IgE antibodies, which bind to mast cells and prime them for future allergic reactions.
• 😀 Upon subsequent exposure to pollen, the IgE-primed mast cells release histamine, leading to inflammation and fluid accumulation in facial tissues.
• 😀 Mast cells are concentrated around the eyes and nose, providing extra protection as these are key entry points for infections.
• 😀 Early exposure to allergens, such as growing up on a farm or having pets, may protect against allergic rhinitis by modulating immune responses.
• 😀 Common symptoms of allergic rhinitis include nasal congestion, red, itchy, swollen eyes, sneezing, and watery discharge from the nose.
• 😀 Diagnosis is typically based on symptoms and can be confirmed through skin prick tests to identify specific allergens.
• 😀 Treatment options include avoiding allergens, using antihistamines to suppress histamine effects, and nasal irrigation to reduce congestion. In severe cases, desensitization therapy can help build tolerance to allergens.

Q & A

What is allergic rhinitis and what causes it?

Allergic rhinitis is nasal inflammation triggered by airborne allergens such as pollen, dust, animal hair, or mold spores. It is often referred to as hay fever and occurs when the body’s immune system reacts to these allergens.

What type of immune response is involved in allergic rhinitis?

Allergic rhinitis involves a type 1 hypersensitivity immune response, which is triggered when the body is exposed to an allergen like pollen. This leads to an activation of immune cells, production of antibodies, and the release of histamine.

How does the immune system react to allergens in allergic rhinitis?

When an allergen like pollen enters the body, it is picked up by immune cells called dendritic cells, which present the allergen to T cells. This activates the T cells, which then stimulate B cells to produce IgE antibodies, causing mast cells to release histamine, leading to inflammation and symptoms.

What role does histamine play in allergic rhinitis?

Histamine, released by mast cells in response to IgE antibodies, causes blood capillaries to dilate and become leaky, leading to fluid accumulation in the facial tissues. This results in symptoms like nasal congestion, red, itchy, and swollen eyes, and sneezing.

Why do mast cells release histamine in allergic rhinitis?

Mast cells release histamine when they are primed by IgE antibodies. This occurs when the body is exposed to an allergen for a second time, leading to an exaggerated immune response and causing inflammation in the nose and eyes.

Can early exposure to allergens help prevent allergic rhinitis?

Yes, there is evidence that early exposure to allergens, such as growing up on a farm or having pets, can reduce the likelihood of developing allergic rhinitis. This is due to a combination of genetic and environmental factors that influence the immune response.

What are the common symptoms of allergic rhinitis?

The symptoms of allergic rhinitis include nasal congestion, itchy, red, swollen eyes, sneezing, and excess fluid in the facial tissues. These symptoms can start within minutes of exposure to allergens and may last for weeks.

How is allergic rhinitis diagnosed?

Allergic rhinitis is typically diagnosed based on the appearance of symptoms, and sometimes through a skin prick test. This test involves placing allergens on the skin and observing for an allergic reaction. Identifying the allergen helps people avoid triggers.

What treatment options are available for allergic rhinitis?

Treatment options for allergic rhinitis include avoiding the allergen, using antihistamines to suppress histamine release, nasal irrigation to clear sinuses, and in some cases, desensitization therapy to gradually increase tolerance to the allergen.

What is desensitization therapy and how does it help with allergic rhinitis?

Desensitization therapy involves exposing the body to small amounts of an allergen, gradually increasing the dose over time. This helps the immune system build tolerance to the allergen and reduces the tendency to produce IgE antibodies in future exposures.