- Person
- Paul Ehrlich
- Lived
- 1854–1915
- Field
- Immunology & chemotherapy
- From
- German
The story
From his student days Paul Ehrlich watched dyes attach themselves to some cells and tissues and ignore others. In his 1885 monograph on the oxygen needs of the body, he injected dyes into laboratory animals and found that organs took them up to very different degrees. The work convinced him that all the processes of life could be traced to physical chemistry taking place inside cells.
His work on dyes, antibodies and drugs came to rest on one unifying principle. Whether a stain was colouring a cell, an antibody neutralising a toxin or a chemical killing a microbe, the substance could only have an effect if it first attached to something specific. He expressed the idea in a Latin maxim, corpora non agunt nisi fixata, which the University of Pittsburgh's Health Sciences Library translates as a drug will only act when bound to its target.
The same idea shaped his side-chain theory of immunity. Borrowing Emil Fischer's 1894 image of an enzyme fitting its substrate like a key in a lock, Ehrlich proposed in 1897, and in full in a 1900 lecture to the Royal Society in London, that cells carry chemical side chains, later called receptors, which bind toxins with precise specificity.
In Frankfurt he applied the principle to drugs. His aim, as his Nobel biography puts it, was to find chemicals with special affinities for disease-causing organisms, so that they would go straight to their targets like magic bullets. He and his assistants tested hundreds of compounds, a search that produced Salvarsan, the first effective treatment for syphilis, in 1909. In 1910 the German artist Karl Goetz made a bronze medal showing Ehrlich at the age of 56; its reverse carries the four Latin words of the maxim.
The Pittsburgh library, which holds one of these medals, describes the phrase as a well-known expression in drug-receptor pharmacology that captures the fundamental concept of the field. Modern drug discovery commonly begins by identifying a target molecule in the body and then searching for compounds that bind to it, and antibody-drug conjugates, which carry a cancer drug to a chosen cell, have partly realised his dream of the magic bullet.
Why it matters
The principle that drugs work by binding to specific targets guides the discovery of nearly every modern medicine, from antibiotics to targeted cancer therapies.
About Paul Ehrlich
Nobel-winning German Jewish physician who imagined the “magic bullet”, founded chemotherapy and, with Salvarsan in 1909, produced the first effective drug against syphilis.
More about Paul Ehrlich
- Paul Ehrlich named and characterised the mast cellWhile still a young scientist, Paul Ehrlich named and characterised the mast cell, the immune cell now known to drive allergic reactions.
- Paul Ehrlich's dyes revealed the blood-brain barrierPaul Ehrlich noticed that dyes injected into the bloodstream coloured nearly every organ except the brain, an early clue to the blood-brain barrier that protects our nervous system.
- Paul Ehrlich's dyes founded modern haematologyUsing the new synthetic dyes of the 1870s and 1880s, Paul Ehrlich learned to tell the different kinds of white blood cells apart, laying the foundations of modern blood science.
- Paul Ehrlich improved the tuberculosis test overnightThe day after Robert Koch announced the tuberculosis bacterium in March 1882, Paul Ehrlich improved Koch's method of staining it, making the deadly germ far easier to detect.
- Paul Ehrlich's "magic bullet" cured syphilisPaul Ehrlich imagined a "magic bullet" that would strike disease without harming the patient, and in 1909 his lab found Salvarsan, the first modern antimicrobial drug and first cure for syphilis.
- Paul Ehrlich treated malaria with a synthetic dyeNoticing that malaria parasites soak up methylene blue, Paul Ehrlich tried the dye as a treatment, and two patients' fevers subsided, an early step toward designed synthetic drugs.
- Paul Ehrlich foresaw antibodies and receptorsPaul Ehrlich's side-chain theory proposed that cells carry receptors that bind specific toxins, an idea about antibodies that helped earn him the 1908 Nobel Prize.
- Paul Ehrlich made diphtheria antitoxin reliableWorking with Emil von Behring in the 1890s, Paul Ehrlich devised ways to measure the strength of diphtheria antitoxin, so doctors could give children safe, reliable doses.
- Paul Ehrlich’s trypan red opened the attack on trypanosomesScreening over 100 dyes in Frankfurt, Paul Ehrlich’s team found trypan red, which killed trypanosomes in infected animals, an early chemotherapy victory that led to arsenic drugs.
Sources
- Treasures from the Rare Book Room: Corpora non agunt nisi fixata University of Pittsburgh Health Sciences Library System
- Paul Ehrlich Wikipedia
Another act of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.