Which type of antibody molecules is involved in ABO - incompatibility reaction?

Options

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

Answer

To answer the question "Which type of antibody molecules is involved in ABO incompatibility reaction?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the ABO Blood Group System**: The ABO blood group system consists of four main blood types: A, B, AB, and O. Each blood type has specific antigens on the surface of red blood cells.

2. **Identify Antigens and Antibodies**: In the ABO system, blood type A has A antigens and anti-B antibodies, blood type B has B antigens and anti-A antibodies, blood type AB has both A and B antigens but no anti-A or anti-B antibodies, and blood type O has no A or B antigens but has both anti-A and anti-B antibodies.

3. **Recognize the Incompatibility Reaction**: An ABO incompatibility reaction occurs when a person receives blood that has antigens not present in their own blood type. For example, if a person with type A blood receives type B blood, the anti-B antibodies in the type A blood will attack the B antigens in the type B blood.

4. **Identify the Type of Antibody Involved**: The antibodies that are primarily involved in the ABO incompatibility reaction are IgM antibodies. IgM is the first antibody produced in response to an infection and is effective in agglutinating (clumping) cells.

5. **Eliminate Other Options**:
- **IgA**: Primarily involved in mucosal immunity, not in blood transfusion reactions.
- **IgE**: Involved in allergic reactions and responses to parasites, not in ABO incompatibility.
- **IgG**: While it plays a role in immune responses, it is not the primary antibody involved in ABO incompatibility.

6. **Conclusion**: Based on the above analysis, the type of antibody molecules involved in the ABO incompatibility reaction is **IgM**.

### Final Answer:
The type of antibody molecules involved in the ABO incompatibility reaction is **IgM**.