When our body is exposed to antigen for second time a relatively faster and high intensity immune response is produced. What is not true about this response?

Options

A. Main antibody formed is IgM
B. Based on memory cells
C. Also known as anamnestic response
D. Gives effective immunity.

Answer

To solve the question regarding the immune response when the body is exposed to an antigen for the second time, we need to analyze the statements related to this response and identify which one is not true. Here’s a step-by-step breakdown of the solution:

### Step-by-Step Solution:

1. **Understanding the Immune Response**:
- When the body encounters an antigen for the first time, it takes time to recognize it and produce antibodies. This initial response is slower and less intense.

2. **Memory Cells Formation**:
- After the first exposure, the body creates memory cells (T-memory and B-memory cells) that "remember" the specific antigen. This is crucial for a faster response during subsequent exposures.

3. **Second Exposure**:
- Upon re-exposure to the same antigen, the immune system can respond more quickly and with greater intensity. This is known as the anamnestic response.

4. **Types of Antibodies**:
- The first antibody produced during the initial response is typically IgM. After that, IgG is produced, which is more effective in combating the pathogen.

5. **Evaluating the Statements**:
- We need to evaluate the statements provided in the question to identify which one is incorrect.
- The statement "Main antibody formed is IgM" is true for the first exposure, but when considering the second exposure, the main antibody produced is IgG due to the presence of memory cells. Therefore, this statement is misleading in the context of the second exposure.

6. **Conclusion**:
- The statement that is not true regarding the immune response upon second exposure to an antigen is that the main antibody formed is IgM. Instead, it is IgG that is primarily produced during the secondary immune response.

### Final Answer:
The statement that is not true about the immune response when the body is exposed to an antigen for the second time is: "Main antibody formed is IgM."

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