Cellular immunology

Article By:

Loftus, Douglas J. Laboratory of Cell Biology, National Cancer Institute, Bethesda, Maryland.

Last reviewed:January 2021

DOI:https://doi.org/10.1036/1097-8542.118100

The field concerning the interactions among cells and molecules of the immune system, and how such interactions contribute to the recognition and elimination of pathogens. Humans (and vertebrates in general) possess a range of nonspecific mechanical and biochemical defenses against routinely encountered bacteria, parasites, viruses, and fungi. The skin, for example, is an effective physical barrier to infection. Basic chemical defenses are also present in blood, saliva, and tears, and on mucous membranes. These defenses are nonspecific in that they may be effective against a broad array of organisms. Nonspecific or innate defense mechanisms offer only limited protection against pathogenic organisms, which can proliferate rapidly and overwhelm these first-line defenses. True immune protection stems from the host's ability to mount responses targeted to specific organisms, and to retain a form of "memory" that results in a rapid, efficient response to a given organism upon a repeat encounter (see illustration). This more formal sense of immunity, termed adaptive immunity, depends upon the coordinated activities of cells and molecules of the immune system. See also: Cell (biology); Immunity; Immunology; Infection; Pathogen; Synthetic immunology

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