The German bacteriologist Paul Ehrlich (1854-1915) advanced the science and practice of medicine by applying the fast-growing achievements of organic chemistry to the problems of disease. He is known for his discovery of Salvarsan.
Paul Ehrlich was born on March 14, 1854, at Strehlen, Upper Silesia. While still at school he took a great interest in chemical experiments and even got the local druggist to compound throat lozenges according to his original prescription.
At first Ehrlich attended Breslau University but found it dull and uninteresting because it lacked biology and organic chemistry, his favorite subjects. Accordingly, he passed on to the new University of Strasbourg, where he experimented with histological staining, but he returned to Breslau in his third term. In 1878 he graduated in medicine at Leipzig. His thesis was a contribution on the theory and practice of histological staining—the conception of the processes in their chemical, technological, and histological aspects—in which his idea of a chemical binding of heterogeneous substances to protoplasm was first expressed. Already in 1876, he had discovered the "mast" cell by its basophilic granules.
Early in his student career Ehrlich started investigations which in spite of their apparent diversity converged on a common principle: the action of drugs as a manifestation of their specific affinity for particular constituents of cells. According to Ehrlich, substances which affect bodily functions do so by virtue of combining with particular components of the animal. In chemical idiom, certain atom groups (side chains) of the drug combine with receptor atom groups of the cellular protoplasm and lead to the action. This was his famous "side-chain theory."
Ehrlich spent several years in Egypt recovering from a severe case of phthisis. On his return to Germany, Robert Koch, from whom Ehrlich had received an understanding of the modern discipline of cellular pathology and also the relation of bacteriology to disease processes, offered him a place in his new Institute for Infectious Diseases. Here Ehrlich perfected methods of preparing and standardizing diphtheria antitoxin from horses. Meanwhile he was appointed director of the State Institute for Serum Research and Serum Control at Steglitz near Berlin. Work on tumors and immunological studies occupied the forefront of his research until about 1909. In 1908 Ehrlich received the Nobel Prize in medicine for his studies on immunity.
The Speyer-Ellissen family of Frankfurt offered to endow a research institute for Ehrlich's work on chemo-therapy. The institute, named George Speyer-Haus, was built, and in 1906 Ehrlich became director. The methods of chemotherapy, that is, treating infections with synthetic compounds antagonistic to pathogenic agents without seriously damaging the host, had arisen in 1891, when it was observed that methylene blue exercises a curative action on human malaria. Before the founding of the institute, Ehrlich had conducted work on an experimental scale with a small staff, and this resulted in a veritable miracle: the cure of a trypanosome infection that was invariably fatal in mice in 3—4 days. Cure followed one subcutaneous injection of a synthetic dye, trypan red, administered within 24 hours of the anticipated time of death. Other drugs were found to possess a degree of therapeutic effect, and certain organic arsenical compounds, "atoxyl" derivatives, also proved to be trypanocidal. From these the drug Salvarsan was derived, which Ehrlich found to be the most efficient curative agent for human syphilis then known, although it was sometimes liable to produce toxic effects. The science of chemotherapy was thus born.
Ehrlich's tremendous achievements were the outcome of a life of unremitting scientific preoccupation to which almost everything was sacrificed. The furor of Salvarsan made him one of the celebrities of his time, both in science and commerce. He died in Bad Homburg, Hesse, on Aug. 20, 1915.
For Ehrlich's own writings see F. Himmelweit, ed., The Collected Papers of Paul Ehrlich (1956). Accounts of Ehrlich's life and work are Herman Goodman, Paul Ehrlich: A Man of Genius and an Inspiration to Humanitarians (1924), and Martha Marquardt, Paul Ehrlich (1951). A sketch of his life is in Theodore L. Sourkes, Nobel Prize Winners in Medicine and Physiology, 1901-1965 (1953; rev. ed. 1966).