In the cell mediated immuno response, T-lymphocytes divide and secrete

Options

A. Antigens
B. Plasmogens
C. Collagens
D. Cytokines

Explanation

### Step-by-Step Solution:

1. **Understanding the Immune Response**: The immune response is the body's defense mechanism against foreign bodies or antigens. It can be categorized into two types: humoral immunity and cell-mediated immunity.

2. **Identifying Cell-Mediated Immunity**: In cell-mediated immunity, T-lymphocytes (T-cells) play a crucial role. This type of immunity is primarily responsible for attacking infected cells directly.

3. **Role of Macrophages**: The process begins when a macrophage, which is a type of immune cell, encounters an infected cell. The macrophage processes the antigen from the infected cell and presents it to T-cells.

4. **Activation of T-Cells**: Upon recognizing the antigen, T-cells, particularly helper T-cells, get activated. These helper T-cells are essential for orchestrating the immune response.

5. **Secretion of Cytokines**: Activated helper T-cells secrete signaling molecules known as cytokines. Cytokines play a vital role in regulating the immune response by activating other immune cells, including cytotoxic T-cells and B-cells.

6. **Division of T-Cells**: The cytokines released stimulate the division of T-cells, including memory T-cells, which are crucial for long-term immunity. These T-cells proliferate and differentiate into effector T-cells that can directly attack and destroy infected cells.

7. **Conclusion**: The primary substance secreted by T-lymphocytes during the cell-mediated immune response is cytokines, which facilitate communication between immune cells and enhance the immune response.

### Final Answer:
In the cell-mediated immune response, T-lymphocytes divide and secrete **cytokines**.

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