The cell which plays a major role in host defense against tumor cells and the cells infected with viruses is

Options

A. B-lymphocytes
B. Interferons
C. NK-cell
D. Neutrophils

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the type of cell that plays a major role in the host defense against tumor cells and cells infected with viruses.

2. **Identifying Key Players in Immune Response**: In the immune system, various cells are involved in defending the body against infections and tumors. Some of these include B-lymphocytes, T-lymphocytes, natural killer (NK) cells, and neutrophils.

3. **Focusing on Tumor and Virus Infections**: Tumor cells and virus-infected cells often evade the immune system. However, certain immune cells are specifically effective against these threats.

4. **Role of Natural Killer (NK) Cells**: Among the immune cells, NK cells are particularly known for their ability to recognize and destroy tumor cells and virus-infected cells. They do not require prior sensitization to act against these cells.

5. **Function of Interferons**: When cells become infected with a virus, they produce proteins called interferons. Interferons are cytokines that help to boost the immune response and inhibit viral replication, but they are not cells themselves.

6. **Conclusion**: The cell that plays a major role in the defense against tumor cells and virus-infected cells is the **Natural Killer (NK) cell**.

**Final Answer**: The cell which plays a major role in host defense against tumor cells and cells infected with viruses is **Natural Killer (NK) cells**.

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