The Immunoglobulin present in mother's milk is

Options

A. IgD
B. IgE
C. IgM
D. IgA

Answer

To determine the immunoglobulin present in mother's milk, we can analyze the different types of immunoglobulins and their presence in breast milk.

### Step-by-Step Solution:

1. **Identify the Types of Immunoglobulins**: There are five main classes of immunoglobulins in the human body: IgA, IgD, IgE, IgG, and IgM. Each has different functions and locations in the body.

2. **Understand the Role of Each Immunoglobulin**:
- **IgA**: This is the primary immunoglobulin found in mucosal areas, including the gastrointestinal tract, respiratory tract, and also in secretions like saliva, tears, and breast milk. It plays a crucial role in mucosal immunity.
- **IgD**: This is mainly found on the surface of B cells and is involved in the initiation of B cell activation. It is not typically found in significant amounts in breast milk.
- **IgE**: This is associated with allergic reactions and is not present in mother's milk.
- **IgG**: This is the most abundant immunoglobulin in the bloodstream and provides the majority of antibody-based immunity against invading pathogens. However, it is not the primary immunoglobulin in breast milk.
- **IgM**: This is the largest antibody and is primarily found in the bloodstream, not in mother's milk.

3. **Conclusion**: Among these immunoglobulins, **IgA** is the one that is predominantly present in mother's milk. It helps protect the infant against infections by providing passive immunity.

4. **Final Answer**: The immunoglobulin present in mother's milk is **IgA**.