Which of the following antibody the strongest agglutination ?

Options

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

Answer

To determine which antibody shows the strongest agglutination, we need to understand the concept of agglutination and the structure of different antibodies.

### Step-by-Step Solution:

1. **Understand Agglutination**:
- Agglutination refers to the clumping of cells, which occurs due to the interaction between antigens (on the surface of cells) and antibodies (produced by the immune system).

**Hint**: Remember that agglutination is a result of antigen-antibody interactions.

2. **Identify Antibody Structure**:
- Antibodies have different structures and valencies. The number of antigen-binding sites on an antibody determines its ability to cause agglutination.

**Hint**: Consider how the structure of an antibody affects its function.

3. **Types of Antibodies**:
- There are five main classes of antibodies: IgG, IgA, IgM, IgE, and IgD.
- Among these, IgM is unique because it is a pentamer, meaning it is composed of five antibody units linked together.

**Hint**: Focus on the structural differences between the antibody classes.

4. **Calculate Binding Sites**:
- Each antibody unit has two antigen-binding sites. Therefore, since IgM is a pentamer, it has a total of 5 x 2 = 10 antigen-binding sites.

**Hint**: Remember that the more binding sites an antibody has, the stronger its agglutination ability.

5. **Compare with Other Antibodies**:
- Other antibodies like IgG, IgA, and IgD are typically monomers, meaning they have only 2 antigen-binding sites. IgE can exist as a dimer but still has fewer binding sites compared to IgM.

**Hint**: Compare the number of binding sites across different antibodies to find the one with the most.

6. **Conclusion**:
- Since IgM has the highest number of antigen-binding sites (10), it shows the strongest agglutination compared to other antibodies.

**Final Answer**: The antibody that shows the strongest agglutination is **IgM**.