What is it about?

This online resource reviews the basics of immunity in the mucosal tracts, i.e., the mouth and pharynx, the gastrointestinal, respiratory, and genital tracts, and their associated glands. The majority of infections arise at or are acquired through these surfaces, and they are also naturally colonized by vast numbers of microbes - the microbiota - most of which are harmless and indeed essential for health. The mucosal immune system is largely separate from - and larger than - the better known circulatory immune system that keeps the internal tissues free of infection.

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Why is it important?

The mucosal immune system has the task of maintaining co-existence with the normal microbiota, keeping it in place without over-reacting to it. It must also avoid reacting adversely against the large quantity of harmless, but potentially antigenic "foreign" material consumed as food, but it must also mount vigorous immune defense against actual pathogens. Balancing these disparate objectives requires an elaborate apparatus of immune cells interacting with the epithelial cells that line the mucosal tracts, to recognize and respond appropriately to the nature of the challenge, whether that response is tolerance, or vigorous defense against dangerous pathogens, or anything in between. It also provides initial immune protection to the newborn through the provision of antibodies and other factors in milk.

Perspectives

Mucosal immunity has sometimes been viewed, mistakenly, as a niche aspect of immunology. However, quantitative assessment of the tissues, cells, and molecular factors involved, as well as consideration of the huge areas represented by mucosal surfaces, coupled with realization that the great majority of infectious diseases either directly afflict or are acquired across these surfaces, reveals that protection of the mucosae is by far the most important function of the entire immune system. While the general principles of immune recognition and response are the same, there are important differences in the delivery of effector cells and molecules, their functional properties, and the regulatory mechanisms involved.

Professor Michael W Russell
University at Buffalo Department of Microbiology & Immunology

Read the Original

This page is a summary of: Mucosal Surfaces: Immunological Protection, February 2016, Wiley,
DOI: 10.1002/9780470015902.a0000942.pub2.
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