Immunology is the branch of medicine concerned with immunity – the ability of the body to resist specific illnesses and diseases. While there has been some understanding of natural immunity since antiquity, its modern phase began in the 18th century, firstly in China and then spreading to Europe.
In 1798, an English country doctor called Edward Jenner realized that milkmaids who had previously been infected with cowpox escaped infection by the more serious smallpox. He thus developed the idea of inoculating patients with cowpox to ward off smallpox. After successfully testing out his hypothesis on unwitting local lad, James Phipps, Jenner’s idea of vaccination gradually spread, despite fierce opposition from parts of the medical firmament. His method proved far safer than that of variolation, so it is Jenner who is widely considered the father of modern immunology.
As scientists in the 19th century got a grip on germ theory (see previous entry here), the field developed at a pace. In particular, Louis Pasteur discovered that chickens infected with a weakened strain of cholera were protected from reinfection. In other words, he realized that introducing a regulated amount of a pathogen (i.e. a disease) into the body can promote the production of what we now know are antibodies to fight off something worse. He was subsequently able to develop vaccines for both rabies and swine erysipelas.
Around the turn of the 20th century, German physician and scientist Paul Ehrlich hypothesized that specific antigens might create particular antibodies, although it was another thirty years or so before his ideas were clinically proven. Then, in the 1940s, research began in earnest into the role of specific cells within the human body’s wider system of disease defence. Much of the work of this period supported the speculative theories of Russian zoologist Élie Metchnikoff, who back in the 1880s had suggested that cells which he called phagocytes (from the Greek for ‘devouring cells’) were crucial in fighting infection. In more recent years, meanwhile, it has been developments in the field of genetics that have opened up the most promising new frontiers in immunology.
What doesn’t kill you makes you stronger
In Greece in the 5th century BCE, Thucydides described how some people survived the plague that was then ravaging Athens, but while there was some understanding that these individuals had developed immunity, exactly how remained a mystery. Little progress was made until the Middle Ages, when a process known as variolation was developed in China. Healthy subjects were exposed to material from the lesions of sufferers from smallpox (then endemic in the country) – most commonly by taking the scab of a pustule, grinding it into a powder and putting it up the nose. Although the treatment was not without risk, it proved remarkably effective in bringing about immunity. By the 18th century the technique had been adopted by the Ottomans, travelled across Europe, and thence been adopted in the Americas.