Biography of Paul Ehrlich

I have just read a biography of Paul Ehrlich by Ernst Bäumler. Ehrlich is one of the great heroes in the advances in medicine in the late nineteenth and early twentieth centuries. I liked the book not for any literary qualities but for the facts it contains. Here is one which is mentioned in the text and which I recommend to the consideration of those people who are against vaccinations. In the Franco-Prussian war the number of German soldiers who died of smallpox was 297, the number of French soldiers who died of smallpox 23400. This difference was due to compulsory vaccination on the German side. This book tells the story of Ehrlich’s life but also contains information about other notable figures in the history of medicine who he was in contact with, for instance Robert Koch, Emil Behring, Louis Pasteur, Emile Roux, Elie Metchnikoff and Joseph Lister. Another interesting fact is that at the time when Ehrlich won the Nobel Prize for medicine in 1908 more than half the prizes awarded up to that time had gone to Germans.

Ehrlich can be seen as the founder of modern immunology. If you open a textbook on immunology one of the first things you encounter is a list of different types of white blood cells. Many of these were discovered and named by Ehrlich, starting with the mast cells. Exceptions are the macrophages, discovered by Mechnikoff, and the different types of lymphocytes which could only be distinguished using techniques much more advanced than those available in Ehrlich’s days. Ehrlich was also the one who discovered and named the complement system. White blood cells all look rather similar under the microscope and the idea which allowed Ehrlich to make progress in distinguishing them was to stain them with various dyes. Ehrlich was known in younger years for the fact that his clothes and the laboratory in which he worked were covered with stains. What Ehrlich observed was that certain dyes were taken up preferentially by certain cells and certain substructures in those cells. This was useful for the study and classification of the cells. Ehrlich developed this further with the idea that dyes which were specific for certain cells, in particular unicellular pathogenic organisms, might be candidates for drugs which could affect those cells.

The first big practical medical success which Ehrlich was involved with was the development of serum treatment, in modern language antibody treatment, for diphtheria. The driving force in this development was Behring and he got a Nobel Prize for that. However without the contributions of Ehrlich this project might have failed. At least it would not have been successful so soon. The two men had a difficult relationship with Behring often being aggressive and Ehrlich forgiving. At Ehrlich’s funeral Behring had prepared a longer speech but in the end only managed to say the following, ‘Du hattest eine empfindsame Seele. Verzeih, wenn wir dir manchmal wehgetan haben’ [You had a sensitive mind. Forgive us if we often hurt you.] Incidentally, Ehrlich was the one to invent the idea of antibodies and that of a receptor in cell biology (Seitenkettentheorie).

Later Ehrlich started a big programme for synthesizing chemical substances and testing their effects on certain organisms, notably that which causes syphilis. A long list was tested, whereby a lot of the hard work leading to the final success was carried out by Sahachiro Hata. He was the one who discovered the effectiveness of the compound number 606 on the list against the causative agent of syphilis. This was later called Salvarsan and revolutionized the treatment of the disease. This was the first example of success of an artificially synthesised drug becoming a cure for a major illness. In this sense Ehrlich can be seen as the founder of chemotherapy, the development and use of chemicals to treat disease. Salvarsan was a tremendous success when it was introduced. It was later superceded by penicillin. Alexander Fleming gave a speech where he talks about how much he was influenced to do his work by what he knew about Ehrlich. Despite the success of Salvarsan it met with a lot of public opposition. It was the same kind of chorus we are familiar with from the reactions to the COVID-19 vaccines. It was claimed that the drug was dangerous, causing many deaths, that it was not effective and that it was too expensive and in fact had only been developed to make money. There are some sad constants in human nature. One positive thing is that one man who ran a campaign of lies about Salvarsan and slander of Ehrlich was sentenced to a year of prison for doing so.