Which one of the cell of cellular barrier of innate immunity is not involved in phagocytosis :-

Options

A. Monocyte
B. Macrophage
C. PMNL-neutrophil
D. Natural killer cell

Answer

To solve the question "Which one of the cell of cellular barrier of innate immunity is not involved in phagocytosis?", we will analyze each option provided:

1. **Monocyte**:
- Monocytes are a type of white blood cell that play a significant role in the immune response. They can differentiate into macrophages and dendritic cells, both of which are involved in phagocytosis. Therefore, monocytes are involved in phagocytosis.

2. **Macrophage**:
- Macrophages are derived from monocytes and are well-known for their ability to engulf and digest cellular debris and pathogens. They are key players in the immune system and are definitely involved in phagocytosis.

3. **PMNL (Polymorphonuclear leukocytes)**:
- PMNLs, commonly referred to as neutrophils, are another type of white blood cell that are highly effective at phagocytosing bacteria and fungi. They are one of the first responders to sites of infection and are involved in phagocytosis.

4. **Natural Killer (NK) Cells**:
- Natural Killer cells are a type of lymphocyte that play a crucial role in the innate immune response. However, their primary function is not phagocytosis. Instead, they are involved in the destruction of infected or cancerous cells through the release of cytotoxic substances and the production of cytokines to enhance the immune response.

Based on this analysis, the cell that is not involved in phagocytosis is:

**Correct Answer: Natural Killer (NK) Cells**

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