Question

Alveolar macrophages.

Hint:

Alveolar macrophages are essential for lung immunity, and their dysfunction can predispose individuals to respiratory infections.

Answer 1

Step 1: Understanding Alveolar Macrophages.
Alveolar macrophages are a type of immune cell found in the alveoli (the air sacs) of the lungs. They play a crucial role in the innate immune defense of the respiratory system by identifying and eliminating pathogens, particulates, and debris that enter the lungs.

Step 2: Function of Alveolar Macrophages.
Alveolar macrophages are the first line of defense against inhaled pathogens. They perform several important functions:
- Phagocytosis: Alveolar macrophages engulf and digest pathogens, dead cells, and other particles in the alveoli.
- Cytokine Production: They release cytokines, which help regulate the immune response and recruit other immune cells to the site of infection.
- Antigen Presentation: Alveolar macrophages can present antigens to T-cells, thus initiating adaptive immune responses.

Step 3: Clinical Relevance.
Impaired function of alveolar macrophages can lead to increased susceptibility to respiratory infections. For example, in diseases like chronic obstructive pulmonary disease (COPD) or pneumonia, the ability of these macrophages to clear pathogens is compromised, leading to increased risk of infection.