How Do Phagocytes Respond to Infections Without Identifying the Pathogen?

[Cheman]

Phagocytosis and chemotaxis...

How can phagocytes know to move towards a site of infection yet not be able to identify what the pathogen/ antigen actually is? ie - be non-specific? How does it manage to respond to it without knowing what it actually is?

Thanks.

 

[Monique]

The easy answer is that when cells get damaged by an injury they start releasing molecules that attract immune cells. The attraction is mediated by the fact that the lining of the bloodvessel near the trauma will start expressing surface molecules that are sticky to the immune cells (monocytes), the immune cell starts to slow down and roll on the bloodvessel wall, until it encounters a spot through which it can penetrate the vessel wall and enter the tissue. Once in the tissue the monocyte differentiates into a phagocytic macrophage.

 

[ravenprp]

Phagocytosis and chemotaxis are two important mechanisms used by the immune system to protect the body against pathogens and foreign substances. Phagocytosis is the process by which specialized cells, called phagocytes, engulf and destroy foreign particles, such as bacteria and viruses. Chemotaxis, on the other hand, is the ability of phagocytes to detect and move towards chemical signals released by damaged tissue or invading microorganisms.

Phagocytes are able to recognize and respond to these chemical signals through specialized receptors on their surface. These receptors are able to detect specific chemical patterns that are associated with pathogens, such as lipopolysaccharides on the surface of bacteria. This allows phagocytes to identify potential threats and initiate a response.

However, phagocytes also have the ability to respond to non-specific signals, such as changes in the concentration of certain chemicals, which can be a sign of tissue damage or infection. This allows them to quickly respond to potential threats, even if they are not able to specifically identify the pathogen.

In addition, phagocytes also have a mechanism called opsonization, where antibodies or other molecules coat the surface of pathogens, making them more recognizable and easier to engulf. This allows phagocytes to respond to a wider range of pathogens and foreign substances, even if they cannot specifically identify them.

Overall, the ability of phagocytes to respond to non-specific signals and use opsonization allows them to quickly and efficiently remove potential threats from the body, even if they are unable to specifically identify them. This is an important aspect of the immune response and helps to protect the body from a variety of pathogens and foreign substances.