Opsonization is a term that refers to an immune process where particles such as bacteria are targeted for destruction by an immune cell known as a phagocyte . The process of opsonization is a means of identifying the invading particle to the phagocyte. Without the opsonization process the recognition and destruction of invading agents such as bacteria would be inefficient.
The process of opsonization begins when the immune system recognizes a particle (e.g., a bacterium) as an invader. The recognition stimulates the production of antibodies that are specific for the antigenic target. Certain antibody molecules are stimulated to bind to the surface of the particle. Typically, the binding molecules are a type of antibody classified as IgG. As well, proteins involved in the complement-mediated clearance of foreign material, specifically a protein designated C3b, can bind to the surface of the foreign object. Proteins such as IgG and C3b, which can promote opsonization, are designated as opsonins.
When the IgG antibodies bind to the invading bacterium, the binding is in a specific orientation. An antibody is somewhat "Y" shaped. The binding of IgG to the bacterium is via the branching arms of the "Y." The stalk of the molecule, which is termed the Fc region, then protrudes from the surface. The Fc region is recognized by a receptor on the surface of an immune cell called a phagocyte. When the Fc region is bound to the phagocytic receptor the invading particle is taken into the phagocyte and enzymatically digested.
The Cb3 complement protein can bind in a nonspecific manner to an invading particle. Phagocytes also contain surface receptors that recognize and bind Cb3. As with IgG, the binding of Cb3 to the phagocytes triggers a process whereby the invading particle is engulfed, surrounded, and taken inside the phagocytic cell for destruction.
Examples of phagocytic cells that can participate in opsonization are neutrophils and monocytes.
Bacteria that are associated with the development of infections typically possess a capsule, which is a layer of carbohydrate material. The capsular material encases the bacterial cell. The carbohydrate is not recognized as readily by the immune machinery of the body as is protein. As well, the penetration of antibodies through the capsule network to the surface of the bacterium is impeded. Thus, possession of a capsule can dampen the opsonization response.
See also Complement; Immunoglobulins and immunoglobulin deficiency syndromes; Immunity, active, passive and delayed
"Opsonization." World of Microbiology and Immunology. . Encyclopedia.com. (April 21, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/opsonization
"Opsonization." World of Microbiology and Immunology. . Retrieved April 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/opsonization
Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).
Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.
Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:
Modern Language Association
The Chicago Manual of Style
American Psychological Association
- Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
- In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.
"opsonization." A Dictionary of Biology. . Encyclopedia.com. (April 21, 2018). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/opsonization
"opsonization." A Dictionary of Biology. . Retrieved April 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/opsonization