Editing Humoral immunity (section)

==History==
The concept of humoral immunity developed based on the analysis of [[antibacterial]] activity of the serum components. [[Hans Buchner (biologist)|Hans Buchner]] is credited with the development of the humoral theory.<ref name= Metch>{{cite book | vauthors = Metchnikoff E | author1-link = Elie Metchnikoff | date = 1905 | url = https://archive.org/details/immunityininfec01metcgoog | title = Immunity in infectious disease | publisher = Cambridge University Press }}</ref> In 1890, Buchner described alexins as "protective substances" that exist in the [[serum (blood)|blood serum]] and other [[Body fluid|bodily fluids]] and are capable of killing [[microorganism]]s. Alexins, later redefined as "complements" by [[Paul Ehrlich]], were shown to be the [[soluble]] components of the innate response that leads to a combination of [[Cellular immunity|cellular]] and humoral immunity. This discovery helped to bridge the features of [[Innate immunity|innate]] and [[acquired immunity]].<ref name= Metch/>

Following the 1888 discovery of the bacteria that cause [[diphtheria]] and [[tetanus]], [[Emil von Behring]] and [[Kitasato Shibasaburō]] showed that disease need not be caused by microorganisms themselves. They discovered that cell-free [[filtrate]]s were sufficient to cause disease. In 1890, filtrates of diphtheria, later named [[diphtheria toxin]]s, were used to [[vaccinate]] animals in an attempt to demonstrate that immunized serum contained an [[antitoxin]] that could neutralize the activity of the toxin and could transfer immunity to non-immune animals.<ref name= G.E>{{cite web | vauthors = Gherardi E | url = http://nfs.unipv.it/nfs/minf/dispense/immunology/lectures/files/foundations_immunology.html | title = The experimental foundations of Immunology | archive-url = https://web.archive.org/web/20110530013459/http://nfs.unipv.it/nfs/minf/dispense/immunology/lectures/files/foundations_immunology.html | archive-date=2011-05-30 | work = Immunology Course Medical School | publisher = University of Pavia }}</ref> In 1897, Paul Ehrlich showed that [[antibodies]] form against the plant [[toxin]]s [[ricin]] and [[abrin]], and proposed that these antibodies are responsible for immunity.<ref name= Metch/> Ehrlich, with his colleague von Behring, went on to develop the [[diphtheria antitoxin]], which became the first major success of modern [[immunotherapy]].<ref name= G.E/> The discovery of specified compatible antibodies became a major tool in the standardization of immunity and the identification of lingering [[infection]]s.<ref name= G.E/>
{| class="wikitable" style="margin: 1em auto 1em auto"
|+ '''Major discoveries in the study of humoral immunity'''<ref name= G.E/>
! Substance|| Activity || Discovery
|-
| Alexin(s)/[[Complement system|Complement]](s)||Soluble components in the serum<br>that are capable of killing microorganisms ||Buchner (1890),<br>Ehrlich (1892)
|-
| [[Antitoxins]]||Substances in the serum that can neutralize the activity of toxins, enabling [[passive immunization]] ||von Behring and Shibasaburō (1890)
|-
| [[Bacteriolysin]]s ||Serum substances that work with the<br>complement proteins to induce bacterial [[lysis]]|| [[Richard Friedrich Johannes Pfeiffer|Richard Pfeiffer]] (1895)
|-
| Bacterial [[agglutinin]]s <br>and [[precipitin]]s|| Serum substances that aggregate bacteria<br>and [[precipitate]] bacterial toxins ||[[Max von Gruber|von Gruber]] and [[Herbert Durham|Durham]] (1896),<br>[[Rudolf Kraus|Kraus]] (1897)
|-
| [[Hemolysis (microbiology)|Hemolysins]] || Serum substances that work with complements<br>to lyse red blood cells || [[Jules Bordet]] (1899)
|-
| [[Opsonin]]s|| Serum substances that coat the outer membrane of foreign substances and enhance the rate of [[phagocytosis]] by [[macrophage]]s||[[Almroth Wright|Wright]] and [[Stewart Ranken Douglas|Douglas]] (1903)<ref name="pmid17788933">{{cite journal | vauthors = Hektoen L | title = Opsonins and Other Antibodies | journal = Science | volume = 29 | issue = 737 | pages = 241–248 | date = February 1909 | pmid = 17788933 | doi = 10.1126/science.29.737.241 | jstor = 1634893 | bibcode = 1909Sci....29..241H | url = https://zenodo.org/record/2404737 }}</ref>
|-
|  [[Antibody]] || Original discovery (1900), antigen-antibody binding hypothesis (1938), produced by B cells (1948), structure (1972), immunoglobulin genes (1976)|| Ehrlich<ref name= Metch/>
|}