How do LEUKOCYTES (white cells) fight foreign materials such as viruses

Question

How do LEUKOCYTES (white cells) fight foreign materials such as viruses

Answer 1

actually your example of virus precludes phagocytosis and macrophage /neutrophil intervention. Macrophages are designed for bacterial destruction. Viruses invade cells by attaching specifically to cell mebrane receptors and entering by stealth. Certain virus "trapping " cells called dendritic cells "allow" themselves to become infected and then degrade the protein coat of the virus  to peptides that are presented to CD8 Tcells to activate them ( arm them ). Then normal cells infected by virus are able to present the same peptides  in th4 context of self MHC proteis to armed T cells which then induce apoptois ( [programmed cell death ) in the infected cell. The other explanations for phagocytosis of bacteria  and production of reactive compounds by macrophages and eosinophils are ok

Answer 2

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Answer 3

by phagocytosis



and by antibodies

Answer 4

This is a VERY complicated subject, and no short answer can really cover it all.

However, I would count at least four major mechanisms:

1) Phagocytosis (as listed by other answerers) is common to all leukocytes, though some are better at it than others.

2) Antibodies (generically, and as listed by others) are produced by a sub-set of leukocytes - B lymphocytes. While other leukocytes *use* antibodies, most do not produce them.

3) Exocytosis of secretory granules containing cytotoxins and pro-inflammatory substances.  Translation:  many leukocytes (e.g. eosinophils) can dump pre-prepared packages of substances that are toxic to living pathogens, and also recruit more white blood cells to the fight. Further, macrophages participate in making components of the Complement System of proteins for fighting bacterial infections.

4) Generation of reactive compounds.  For example, neutrophils have the enzyme myeloperoxidase which allows them to make/release hypochlorous acid to fight infection.  They also have NADPH oxidase, which allows them to generates bursts of superoxide for the same purpose.

The interplay between the many leukocyte classes is complex, leading to a tightly orchestrated response to infection and foreign substances. The above classification is therefore crude, and one could easily come up with more categories.

Answer 5

-by engulfing the bacteria by phagocytosis and digesting them by special enzymes. And then releasing the digested material.