The predominant antibody in saliva is

Options

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

Answer

To determine the predominant antibody in saliva, we can follow these steps:

### Step 1: Understand the Role of Antibodies
Antibodies are proteins produced by the immune system to help fight infections. They come in different classes, each with specific functions and locations in the body.

### Step 2: Identify the Antibody Classes
The main classes of antibodies are:
- **IgG**: The most abundant antibody in blood and extracellular fluid, important for long-term immunity.
- **IgA**: Found in mucosal areas, such as the gut, respiratory tract, and saliva, playing a crucial role in mucosal immunity.
- **IgM**: The first antibody produced in response to an infection.
- **IgD**: Primarily functions as a receptor on B cells and is found in small amounts in the blood.

### Step 3: Focus on Saliva
Saliva is a secretion that plays a vital role in digestion and oral health. It also contains various components that contribute to the immune defense in the oral cavity.

### Step 4: Identify the Predominant Antibody in Saliva
Among the antibodies listed (IgG, IgA, IgM, IgD), the predominant antibody found in saliva is **IgA**. This is because IgA is specifically designed to be secreted in mucosal areas, including saliva, to protect against pathogens.

### Conclusion
Therefore, the correct answer to the question "The predominant antibody in saliva is" is **option B: IgA**.

---