Which antibody is excreted through faeces ?

Options

A. IgG
B. IgA
C. IgM
D. both 1 and 2

Answer

**Step-by-Step Solution:**

1. **Understanding Antibodies**: Antibodies are proteins produced by the immune system to identify and neutralize pathogens like bacteria and viruses. There are several classes of antibodies, including IgA, IgG, and IgM.

2. **Identifying the Antibodies**: The question asks specifically about which antibody is excreted through feces. The options provided are:
- IgG (Immunoglobulin G)
- IgA (Immunoglobulin A)
- IgM (Immunoglobulin M)
- Both 1 and 2 (IgG and IgA)

3. **Role of IgA**: Immunoglobulin A (IgA) is primarily found in mucosal areas, such as the gut, respiratory tract, and urogenital tract. It plays a crucial role in mucosal immunity and is secreted in bodily fluids, including saliva, tears, and importantly, feces.

4. **Role of IgG**: Immunoglobulin G (IgG) is the most abundant antibody in the bloodstream and is crucial for systemic immunity. While it is primarily found in blood and extracellular fluid, some IgG can also be found in feces, especially in conditions like inflammatory bowel disease (IBD).

5. **Role of IgM**: Immunoglobulin M (IgM) is the first antibody produced in response to an infection. It is mainly found in the blood and lymphatic fluid and is not typically excreted in feces.

6. **Conclusion**: Based on the roles of these antibodies, both IgA and IgG can be excreted through feces, especially during conditions that stimulate their production, such as infections or inflammatory bowel disease. Therefore, the correct answer is "Both 1 and 2" (IgG and IgA).

**Final Answer**: Both 1 and 2 (IgG and IgA) are excreted through feces.

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