Question

1. What is phagocytosis? What cell types carry this out? What is opsonization?

2. What strategies do pathogens have to avoid the extracellular immune response?

Answer 1

1) Phagocytosis is a type of endocytosis. In this process, cell uses its plasma membrane to engulf a large particle, produces an internal compartment called the phagosome.

Immune cells that perform phagocytosis are neutrophils, macrophages,dendritic cells, and B lymphocytes.

Opsonization is an immune process in which particles such as bacteria are destructed by an immune cell known as a phagocyte. Opsonization is a process which means to identify the invading particle to the phagocyte.

2) Pathogens can evade immune response by altering its antigens; this process is especially important for extracellular pathogens. Pathogens can invade immune system by changing the non-essential epitopes rapidly on their surface, while keeping the essential epitopes hidden. Pathogens can also remain confined in regions inaccessible to phagocytes. Some pathogens can avoid provoking an overwhelming inflammatory response. Some pathogens and their products are able to inhibit phagocyte chemotaxis. By this way, pathogens can avoid the extracellular immune response.