What is oxygen-dependent phagocytosis?

The oxygen-dependent pathway (oxidative burst) involves the generation of reactive oxygen species (ROS) such as superoxide radicals and hydrogen peroxide. These highly reactive radical molecules react with proteins, lipids and other biological molecules to kill the pathogen.

What is oxygen-dependent mechanism?

This method of killing invading microbes by using the reactive oxygen-containing molecules is referred to as oxygen-dependent intracellular killing, of which there are two types. The first type is the oxygen-dependent production of a superoxide, which is an oxygen-rich bacteria-killing substance.

What are microbicidal mechanisms?

The host microbicidal mechanisms (a) include the NOX2 (also known as CYBB) NADPH oxidase, the inducible NO synthase (iNOS), iron scavengers and exporters, such as lactoferrin and natural resistance-associated macrophage protein 1 (NRAMP1; also known as SLC11A1), plus antimicrobial peptides and proteins that …

What is oxygen independent?

In the ultrastructural sense, oxygen-independent killing of bacteria requires the deposition of a bactericidal component (granule proteins) or the establishment of a hostile, non-physiologic environment in the phagolysosome.

Does phagocytosis require oxygen?

Phagocytic leukocytes consume oxygen and generate reactive oxygen species in response to appropriate stimuli.

What is the mechanism of phagocytosis?

Phagocytosis is a process by which cells ingest large particles (> 0.5 micrometers) into membrane-bound vesicles called phagosomes, which are then targeted to the lysosomes for enzymatic degradation. Phagocytosis is greatly enhanced by the opsonization of the bacteria.

How are phagocytes adapted to their function?

As mentioned, phagocytic cells adapt to specific microenvironments in their utilization of fuels to derive cellular metabolism. Moreover, all cells are sensitive to alterations in their microenvironment; thus it is clear that metabolic alterations in immune cells underlie a central component of pathology.

Which function is associated with phagocytes in the blood?

Phagocytes are a type of white blood cell that use phagocytosis to engulf bacteria, foreign particles, and dying cells to protect the body. They bind to pathogens and internalise them in a phagosome, which acidifies and fuses with lysosomes in order to destroy the contents.

Does IgM Opsonize?

There are no FcµRs on phagocytes, so IgM cannot opsonize in this manner. However, a single molecule of IgM can activate complement through the classical pathway, leading to the deposition of many C3b molecules that can act as opsonins.

How is a phagocyte activated?

Phagocytosis initiates when phagocytic receptors engage ligands on the particle to be ingested. Then, receptors activate signaling pathways that change the membrane composition and control the actin cytoskeleton, resulting in the formation of membrane protrusions for covering the particle.

What are the steps of phagocytosis in the order in which they occur?

11.3E: Phagocytosis

  • Step 1: Activation of the Phagocyte.
  • Step 2: Chemotaxis of Phagocytes (for wandering macrophages, neutrophils, and eosinophils)
  • Step 3: Attachment of the Phagocyte to the Microbe or Cell.
  • Step 4: Ingestion of the Microbe or Cell by the Phagocyte.

What contributes to phagocytosis in white blood cells?

The proteins that coat microbes are called opsonins. These include antibodies (IgG) and proteins of the complement system (C3b, C4b). This facilitates phagocytosis as the phagocytes have receptors for these opsonins, which makes phagocytosis much quicker and more efficient.