Answer: D - PMNs do not present antigen; their main function is phagocytosis of materials, as well as producing cytokine.
PMNs, or polymorphonuclear leukocytes, are a type of white blood cell that plays a crucial role in the innate immune system. These cells are also known as neutrophils because they do not have any specific staining properties and are therefore "neutral" in color. PMNs are the most abundant type of white blood cells, accounting for approximately 60% of all leukocytes in the human body.
The primary function of PMNs is to detect, engulf, and destroy invading pathogens such as bacteria, fungi, and viruses. They do this through a process called phagocytosis, where they surround the pathogen and internalize it within a vesicle called a phagosome. Once inside the phagosome, the PMNs use a combination of enzymes and reactive oxygen species to degrade and kill the pathogen.
PMNs are also involved in the inflammatory response, which is the body's natural reaction to tissue damage or infection. When activated by signals from damaged tissue or invading pathogens, PMNs move from the bloodstream to the site of infection, where they release a variety of chemical mediators that attract other immune cells to the area. This leads to the classic signs of inflammation, such as redness, swelling, and heat.
In addition to their role in fighting infection and inflammation, PMNs are also important in wound healing. They release growth factors and other molecules that stimulate tissue repair and regeneration, and they can also act as a physical barrier to prevent further infection.
Overall, PMNs play a crucial role in the immune system's ability to fight infection and maintain tissue homeostasis. Dysfunction or deficiency in these cells can lead to an increased susceptibility to infections or chronic inflammatory diseases.
