Immunity? What is it? When it was first described? Who discovered Vaccines?

Immunity as described in English dictionary means 'special exemption' or 'protected from infectious disease’[1]. Well the history behind the advent of concept and theories on immunity were not as simple as these definitions.

The Earliest written note on Immunity is dated back to 430 BC, a time which needs to be highlighted for one of the most significant war that is the Peloponnesian War, and the text or rather the account on the most drastic and still speculative Plague of Athens that occurred that time was written by Thucydides, the great historian of the Peloponnesian War. He presented a detailed account on all its symptoms, its occurrence yet people find that it was added to bring a dramatic twist [2]. The topic of our concern forms the most important part of his account in which he wrote that only those who had recovered from the plague could nurse the sick because they would not contract the disease a second time [3], which was the beginning of understanding the concept of immunity because it clearly reflected the ones who contracted the disease for the first time were now immune to it.

The Chinese and Turks were known to be the first one to induce immunity deliberately by technique called variolation which was later carried forward by Edward Jenner, in 1798. She found out a method to inoculate cow pox pustule into people and that resulted in making them immune to small pox [3].

Next was Louis Pasteur who had succeeded in growing the bacterium thought to cause fowl cholera in culture and then through his experiments on chicken it was hypothesized and proved that aging had weakened the virulence

of the pathogen and that such an attenuated strain might be administered to protect against the disease. He

called this attenuated strain a vaccine (from the Latin vacca, meaning “cow”), in honor of Jenner’s work with cowpox inoculation [3].

Till now the concept of introducing a vaccine for immunity was known but now came further queries….

Image Source: "The Athenian Plague"  The Art of Nicolas Poussin (Link: https://donbarone.selfip.net/Poussin%20Thumbs%208.htm)

How did Vaccination work? “Humoral or Cellular” The Controversy update!

Emil von Behring and Shibasaburo Kitasato in 1890 gave the first insights into the mechanism of immunity, earning von Behring the Nobel prize in medicine in 1901. Von Behring and Kitasato demonstrated that serum(the liquid, noncellular component of coagulated blood) from animals previously immunized to diphtheria could transfer the immune state to unimmunized animals. In search of the protective agent, various researchers during the next decade demonstrated that an active component from immune serum could neutralize toxins, precipitate toxins, and agglutinate (clump) bacteria. In each case, the active agent was named for the activity it exhibited: antitoxin, precipitin, and agglutinin, respectively [3].

Initially, a different serum component was thought to be responsible for each activity, but during the 1930s, mainly through the efforts of Elvin Kabat, a fraction of serum first called gamma-globulin (now immunoglobulin) was shown to be responsible for all these activities. The active molecules in the immunoglobulin fraction are called antibodies. Because immunity was mediated by antibodies contained in body fluids (known at the time as humors), it was called humoral immunity. In 1883, even before the discovery that a serum component could transfer immunity, Elie Metchnikoff demonstrated that cells also contribute to the immune state of an animal. He observed that certain white blood cells, which he termed phagocytes, were able to ingest (phagocytose) microorganisms and other foreign material. Noting that these phagocytic cells were more active in animals that had been immunized, Metchnikoff hypothesized that cells, rather than serum components, were the major effector of immunity. The active phagocytic cells identified by Metchnikoff were likely blood monocytes and neutrophils. In due course, a controversy developed between those who held to the concept of humoral immunity and those who agreed with Metchnikoff ’s concept of cell-mediated immunity. It was later shown that both are correct—immunity requires both cellular and humoral responses [3].

Forty-eight days later Jenner injected smallpox matter into the boy. Miraculously, it had no effect. This was the first recorded vaccination.

Image Source:Ebin Rushed Pharmacy www.ebinrushed.com

Watch the Popular Edward Jenner Story in the you tube channel, a complete 9 videos for better look at history coming live

here is the YouTube Link: https://www.youtube.com/channel/HCSp9qt2gh6Do ( You may watch the video in our site, in the videos gallery)

References: 

[1] Oxford English dictionary

[2] The Plague of Athens essay by Chirstos 1(https://www.ancientgreece.com)

[3] Chapter 1, Overview of the Immune System, Immunology, Kuby 5^th Editon