53. Which one of the Immunoglobulins (Ig) cause type-I hypersensitive immune reaction?
(a)IgA
(b)IgE
(c)IgG
(d)IgM

Article:

Introduction

Type-I hypersensitivity refers to allergic reactions that occur rapidly after exposure to certain allergens. These immune responses are typically mediated by IgE immunoglobulins, a specific class of antibodies that play a central role in allergic reactions. In this article, we will explore the role of IgE in Type-I hypersensitivity and how it triggers allergic reactions in the body. Additionally, we will distinguish IgE from other immunoglobulins, such as IgA, IgG, and IgM, to better understand why it is specifically responsible for these hypersensitive immune responses.

What is Type-I Hypersensitivity?

Type-I hypersensitivity, also known as immediate hypersensitivity, is an allergic reaction that occurs when the body’s immune system overreacts to harmless substances, such as pollen, dust mites, or certain foods. The reaction is typically fast-acting, occurring within minutes of exposure to the allergen.

This immune reaction involves the release of various chemicals, such as histamines, that trigger symptoms like itching, swelling, sneezing, and difficulty breathing. In severe cases, it can lead to anaphylaxis, a life-threatening condition.

The Role of IgE in Type-I Hypersensitivity

The key player in Type-I hypersensitivity reactions is the IgE immunoglobulin. When an individual is exposed to an allergen for the first time, their immune system produces IgE antibodies specific to that allergen. These IgE antibodies then bind to certain immune cells, such as mast cells and basophils, which are found in various tissues throughout the body.

Upon subsequent exposure to the same allergen, the IgE antibodies on these immune cells recognize the allergen and trigger the release of various chemicals, including histamine. This release of histamine is what causes the typical symptoms of an allergic reaction, such as itching, hives, and swelling.

IgE vs Other Immunoglobulins

While IgE is the primary antibody involved in Type-I hypersensitivity, it is important to understand how it compares to other immunoglobulins:

1. IgA: Primarily found in mucous membranes, such as in the respiratory and gastrointestinal tracts. It plays a key role in defending against infections, not in allergic reactions.

2. IgG: The most abundant antibody in blood circulation, IgG is involved in antibody-mediated immune responses, such as neutralizing toxins and pathogens. However, it does not typically trigger Type-I hypersensitivity.

3. IgM: The first antibody produced in response to an infection, IgM is involved in initiating the immune response but does not contribute to Type-I hypersensitivity.

Symptoms of Type-I Hypersensitivity

Symptoms of a Type-I hypersensitivity reaction can vary depending on the allergen involved and the severity of the immune response. Common symptoms include:

• Sneezing

• Itchy eyes or skin

• Runny nose

• Swelling or hives

• Wheezing or difficulty breathing

• Anaphylaxis (in severe cases)

Answer to the Question:

The correct answer to the question of which immunoglobulin causes Type-I hypersensitivity is:

(b) IgE

IgE antibodies play the central role in Type-I hypersensitive immune reactions, mediating allergic responses to a variety of allergens.

Conclusion

IgE is the key immunoglobulin involved in Type-I hypersensitivity, which leads to allergic reactions upon subsequent exposure to an allergen. Understanding the role of IgE in these immune responses is crucial for diagnosing and managing allergies. If you or someone you know experiences allergic reactions, it is important to recognize the symptoms of Type-I hypersensitivity and consult with a healthcare provider for appropriate treatment.