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.