Paul Ehrlich: Chemical Dyes, Compound 606 and the Salvarsan Libel Trial

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Paul Ehrlich was born in 1854 into a Jewish family in Prussian Silesia, the son of an innkeeper and lottery collector. His cousin Carl Weigert's microtome sliced tissue so thin it looked transparent, and Ehrlich's 1878 dissertation used industrial dyes to make cell structures visible according to their chemical affinity. He identified mast cells, learned to fix blood smears by heating them on a slide, and sorted white blood cells by how they took up stains. After Robert Koch announced the tuberculosis bacterium in 1882, Ehrlich improved the stain used to see it and became Koch's lifelong friend. At Koch's institute he fed mice rising doses of ricin and abrin and, by swapping nursing pups, proved immunity passed through breast milk rather than heredity.

He made Emil Behring's diphtheria antiserum work in 1894, but Behring squeezed him to an 8 percent share and won the first Nobel Prize in medicine alone in 1901. Ehrlich then set a standard for serum strength and developed his side chain theory of receptors and antibodies, sharing the 1908 Nobel Prize with Élie Metchnikoff. Hunting a magic bullet, he and Sahachiro Hata found compound 606, arsphenamine, which cured syphilis in animals and was sold by Hoechst as Salvarsan in 1910. Critics claimed it encouraged immorality, antisemitic attacks followed, and in 1914 an accuser was charged with criminal libel. Ehrlich was vindicated in court but fell into depression and died of a heart attack in 1915 at 61.

• He named mast cells after a German word for animal fattening feed, thinking their granules were nourishment.
• His serum standard was the toxin-antiserum mix that killed a guinea pig in exactly four days.
• He coined horror autotoxicus, wrongly holding that the body never attacks itself, and his student Ernest Witebsky later proved autoimmunity.
• Methylene blue cured two malaria patients, launching his search for a grand sterilizing therapy.
• The Nazis suppressed a 1940 Hollywood film about him, and a mob slashed his portrait during Kristallnacht.