Which antibody is called secretery antibodies

Options

A. `I_(g)E`
B. `I_(g)A`
C. `I_(g)G`
D. `I_(g)M`

Answer

**Step-by-Step Solution:**

1. **Understanding Antibodies**: Antibodies are proteins produced by the immune system to identify and neutralize foreign objects like bacteria and viruses. There are different classes of antibodies, known as immunoglobulins.

2. **Identifying the Types of Antibodies**: The question provides several options: IgE, IgA, IgG, and IgM. Each of these antibodies has specific functions and locations within the body.

3. **Focus on Mucosal Immunity**: Among these, IgA (Immunoglobulin A) is particularly important for mucosal immunity. It is predominantly found in mucosal linings, which are the membranes lining the body's cavities and passages that communicate with the outside.

4. **Secretory Function of IgA**: IgA is referred to as the "secretory antibody" because it is found in various secretions such as saliva, tears, sweat, breast milk, and mucus. These secretions act as a first line of defense against pathogens entering the body.

5. **Structure of IgA**: IgA is often found in a dimeric form, meaning two IgA molecules join together, which enhances its ability to function in secretions.

6. **Conclusion**: Based on the above points, the antibody that is called secretory antibodies is IgA.

**Final Answer**: IgA is called secretory antibodies.

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