Humoral immunity
Humoral immunity is the aspect of
The study of the
Humoral immunity refers to antibody production and the coinciding processes that accompany it, including:
History
The concept of humoral immunity developed based on the analysis of
Following the 1888 discovery of the bacteria that cause
Substance | Activity | Discovery |
---|---|---|
Alexin(s)/Complement(s) | 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, enabling passive immunization |
von Behring and Shibasaburō (1890) |
Bacteriolysins | Serum substances that work with the complement proteins to induce bacterial lysis |
Richard Pfeiffer (1895) |
Bacterial agglutinins and precipitins |
Serum substances that aggregate bacteria and precipitate bacterial toxins |
von Gruber and Durham (1896), Kraus (1897) |
Hemolysins | Serum substances that work with complements to lyse red blood cells |
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)[4] |
Antibody | Original discovery (1900), antigen-antibody binding hypothesis (1938), produced by B cells (1948), structure (1972), immunoglobulin genes (1976) | Ehrlich[2] |
Antibodies
Immunoglobulins are glycoproteins in the immunoglobulin superfamily that function as antibodies. The terms antibody and immunoglobulin are often used interchangeably. They are found in the blood and tissue fluids, as well as many secretions. In structure, they are large Y-shaped globular proteins. In mammals there are five types of antibody: immunoglobulin A, immunoglobulin D, immunoglobulin E, immunoglobulin G, and immunoglobulin M. Each immunoglobulin class differs in its biological properties and has evolved to deal with different antigens.[5] Antibodies are synthesized and secreted by plasma cells that are derived from the B cells of the immune system.
An antibody is used by the acquired immune system to identify and neutralize foreign objects like bacteria and viruses. Each antibody recognizes a specific antigen unique to its target. By binding their specific antigens, antibodies can cause agglutination and precipitation of antibody-antigen products, prime for phagocytosis by macrophages and other cells, block viral receptors, and stimulate other immune responses, such as the complement pathway.
An incompatible
Antibody production
In humoral immune response, the B cells first mature in the bone marrow and gain B-cell receptors (BCRs) which are displayed in large numbers on the cell surface.[6]
These membrane-bound protein complexes have antibodies which are specific for antigen detection. Each B cell has a unique antibody that binds with an antigen. The mature B cells then migrate from the bone marrow to the lymph nodes or other lymphatic organs, where they begin to encounter pathogens.
B cell activation
When a B cell encounters an antigen a signal is activated, the antigen binds to the receptor and is taken inside the B cell by
B cell proliferation
The B cell waits for a helper T cell (TH) to bind to the complex. This binding will activate the TH cell, which then releases cytokines that induce B cells to divide rapidly, making thousands of identical clones of the B cell. These daughter cells either become plasma cells or memory cells. The memory B cells remain inactive here; later, when these memory B cells encounter the same antigen due to reinfection, they divide and form plasma cells. On the other hand, the plasma cells produce a large number of antibodies which are released freely into the circulatory system.
Antibody-antigen reaction
These antibodies will encounter antigens and bind with them. This will either interfere with the chemical interaction between host and foreign cells, or they may form bridges between their antigenic sites hindering their proper functioning. Their presence might also attract macrophages or killer cells to attack and phagocytose them.
Complement system
The complement system is a
Activation of this system leads to cytolysis,
Three biochemical pathways activate the complement system: the
These processes differ only in the process of activating C3 convertase,[9]
See also
- Cell-mediated immunity (vs. humoral immunity)
- Immune system
- Polyclonal response
- Serology
References
- ^ ISBN 0-8153-3642-X.
- ^ Metchnikoff E (1905). Immunity in infectious disease. Cambridge University Press.
- ^ a b c d Gherardi E. "The experimental foundations of Immunology". Immunology Course Medical School. University of Pavia. Archived from the original on 2011-05-30.
- PMID 17788933.
- ISBN 9781683672111.
- ^ "Humoral Immune Response". Boundless. 2016-05-26. Archived from the original on 2016-10-12. Retrieved 2017-04-15.
- ^ a b Janeway Jr CA, Travers P, Walport M, Shlomchik MJ (2001). "B-cell activation by armed helper T cells". Immunobiology: The Immune System in Health and Disease. (5th ed.).
- PMID 19388161.
- ^ Janeway Jr CA, Travers P, Walport M, Shlomchik MJ (November 21, 2001). "The complement system and innate immunity". Immunobiology: The Immune System in Health and Disease (5th ed.). New York: Garland Science – via www.ncbi.nlm.nih.gov.
Further reading
- Meltzer SJ, Norris C (November 1897). "The Bactericidal Action of Lymph Taken From the Thoracic Duct of the Dog". The Journal of Experimental Medicine. 2 (6): 701–709. PMID 19866859.