Conversion of antigen into harmless insoluble matter by binding of antibody to it is

Options

A. Complement system
B. Opsonization
C. Activation
D. Agglutination

Answer

**Step-by-Step Solution:**

1. **Understanding Antigens and Antibodies**:
- Antigens are foreign substances that induce an immune response in the body. They can be proteins, polysaccharides, or other molecules found on the surface of pathogens.
- Antibodies are proteins produced by the immune system that specifically recognize and bind to antigens.

2. **The Process of Binding**:
- When an antibody binds to an antigen, it forms an antigen-antibody complex. This binding is crucial for the immune response as it helps neutralize the harmful effects of the antigen.

3. **Formation of Harmless Insoluble Matter**:
- The binding of antibodies to antigens can lead to the conversion of the antigen into a harmless form. This process often results in the agglutination of particles, where the antigen-antibody complexes clump together.

4. **Definition of Agglutination**:
- The specific term for the conversion of antigens into harmless insoluble matter by the binding of antibodies is called "agglutination." During agglutination, the clumped particles can no longer circulate freely in the bloodstream.

5. **Role of IgM**:
- Immunoglobulin M (IgM) is particularly effective in agglutination due to its structure, which allows it to bind multiple antigens simultaneously, leading to the formation of large complexes that can be easily cleared by the immune system.

6. **Conclusion**:
- Therefore, the conversion of antigen into harmless insoluble matter by the binding of antibody to it is known as "agglutination."

**Final Answer**: Agglutination

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