Which Ig is produced in primary immune response?

Options

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

Explanation

**Step-by-Step Solution:**

1. **Understanding Immunoglobulins (Ig):** Immunoglobulins, or antibodies, are proteins produced by the immune system to identify and neutralize foreign objects like bacteria and viruses.

2. **Identifying the Options:** The question provides four types of immunoglobulins: IgA, IgE, IgG, and IgM. We need to determine which of these is produced during the primary immune response.

3. **Analyzing IgA:** IgA is primarily found in mucosal areas, such as the intestines, respiratory tract, and urogenital tract. It plays a crucial role in mucosal immunity but is not the first antibody produced in response to an antigen.

4. **Analyzing IgE:** IgE is associated with allergic reactions and responses to parasitic infections. It is not the primary antibody produced during the initial immune response.

5. **Analyzing IgG:** IgG is the most abundant antibody in the blood and is produced later in the immune response, typically after IgM. It can persist for a long time, sometimes for a lifetime, but it is not the first antibody produced.

6. **Analyzing IgM:** IgM is the first immunoglobulin produced in response to an antigen during the primary immune response. It appears within days to weeks after exposure to the antigen and is temporary, eventually being replaced by IgG.

7. **Conclusion:** Based on the analysis, the correct answer to the question is **IgM**, as it is the first antibody produced during the primary immune response.

**Final Answer:** The immunoglobulin produced in the primary immune response is **IgM**.

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