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Humoral immunity facts for kids

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The humoral immune system is a part of the immune system which defends the body against invading organisms and other foreign material.

The humeral part is done by macromolecules outside the cells. These may be secreted antibodies, complement proteins, or certain antimicrobial peptides. Their job is to attack bacteria (and other foreign substances) which are loose in the blood stream or other fluids. In older medicine, these fluids were called "humors". Both the more primitive innate immune system, and the later acquired or adaptive immune system of vertebrates, have humoral components.

The humeral immune system contrasts with the cell-mediated immunity. That involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.

How the humoral system works

The main cells that make it work are the B cells, which create and secrete antibodies that seek out the invaders and attach to them. Once the invader is coated in antibodies, this targets the invader for destruction by other parts of the immune system. Before the B cell can create antibodies, it first needs T helper cells to 'teach' the B cell about details of the incoming invader. This is a key part of the adaptive immune system, and the reference attached here summarizes the process.

The production of antibodies tailor-made to combat particular bacteria is the most important element, but there are a number of other humeral defenses from the more primitive innate immune system.

Major discoveries in the study of humoral immunity
Substance Activity Discovery
Soluble components in the serum
that are capable of killing microorganisms
Buchner (1890),
Ehrlich (1892)
Antitoxins Substances in the serum that can neutralize
the activity of toxins. This is passive immunization
von Behring and Kitasato (1890)
Bacteriolysins Serum substances that work with the
complement proteins to induce bacterial lysis
Richard Pfeiffer (1895)
Bacterial agglutinins
and precipitins
Serum substances that agglutinate bacteria
and precipitate bacterial toxins
von Gruber and Durham (1896),
Kraus (1897)
Haemolysins Serum substances that work with complement
to lyse red blood cells
Belfanti and Carbone (1898)
Jules Bordet (1899)
Opsonins Serum substances that coat the outer membrane
of foreign substances and enhance the rate of
phagocytosis by macrophages
Wright and Douglas (1903)
Antibody Formation (1900), antigen-antibody binding
hypothesis (1938), produced by B cells (1948),
structure (1972), immunoglobulin genes (1976)
Founder: P Ehrlich
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