Lysis of foreign cell is initiated by antibodies of:

Options

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

Answer

To solve the question regarding which antibodies initiate the lysis of foreign cells, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Antibodies**: Antibodies, also known as immunoglobulins, are proteins produced by the immune system to identify and neutralize foreign objects like bacteria and viruses.

2. **Identifying the Types of Antibodies**: The question provides four options, which include different combinations of antibodies: IgM, IgG, IgA, IgD, and IgE.

3. **Role of IgM**:
- IgM is the largest antibody and is the first antibody produced in response to an initial exposure to an antigen.
- It can bind to complement components and activate the classical pathway, leading to cytolysis (lysis of foreign cells).

4. **Role of IgG**:
- IgG is the most common antibody found in blood circulation.
- It is produced by plasma B-cells and can also bind to pathogens, facilitating their destruction and lysis.

5. **Evaluating Other Antibodies**:
- IgA primarily plays a role in mucosal immunity and does not directly initiate lysis of foreign cells.
- IgD is mainly involved in the activation of B-cells and does not have a significant role in lysis.
- IgE is associated with allergic reactions and defense against parasitic infections but does not directly cause lysis of foreign cells.

6. **Conclusion**: Based on the roles of the antibodies, both IgM and IgG are responsible for initiating the lysis of foreign cells. Therefore, the correct answer is **IgM and IgG**.

### Final Answer:
The lysis of foreign cells is initiated by antibodies of **IgM and IgG**.

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