Élie Metchnikoff

(left) and Metchnikoff Metchnikoff was born in the village of , Kharkov Governorate, in the Russian Empire, now located in Kupiansk Raion, Kharkiv Oblast in Ukraine. He was the youngest of five children of Ilya Ivanovich Mechnikov, an officer of the Imperial Guard. In 1856, Metchnikoff entered the Kharkov Lycée, where he developed his interest in biology. Convinced by his mother to study natural sciences instead of medicine, he tried in 1862 to study biology at the University of Würzburg, but the German academic session would not start by the end of the year. Metchnikoff thus enrolled at Kharkov Imperial University for natural sciences, completing his four-year degree in two years. In 1864, he traveled to Germany to study marine fauna on the small North Sea island of Heligoland. He was advised by the botanist Ferdinand Cohn to work with Rudolf Leuckart at the University of Giessen. It was in Leuckart's laboratory that he made his first scientific discovery of alternation of generations (sexual and asexual) in nematodes (Chaetosomatida) and then at the Ludwig-Maximilians-Universität München. In 1865, while at Giessen, he discovered intracellular digestion in flatworm, and this study influenced his later works. Moving to Naples the next year he worked on a doctoral thesis on the embryonic development of the cuttle-fish Sepiola and the crustacean Nebalia. A cholera epidemic in the autumn of 1865 made him move to the University of Göttingen, where he worked briefly with W. M. Keferstein and Jakob Henle. In 1867, he returned to Russia to receive his doctorate with Alexander Kovalevsky from the University of Saint Petersburg. Together they won the Karl Ernst von Baer prize for their theses on the development of germ layers in invertebrate embryos. ==Career and achievements==

Metchnikoff was appointed docent at the newly established Imperial Novorossiya University (now Odesa University). Only twenty-two years of age, he was younger than his students. After being involved in a conflict with a senior colleague over attending scientific meetings, he transferred to the University of Saint Petersburg in 1868, where he experienced a worse professional environment. In 1870 he returned to Odessa to take up the appointment of Titular Professor of Zoology and Comparative Anatomy. In 1887, he observed that leukocytes isolated from the blood of various animals were attracted towards certain bacteria. The first studies of leukocyte killing in the presence of specific antiserum were performed by Joseph Denys and Joseph Leclef, followed by Leon Marchand and Mennes between 1895 and 1898. Almroth E. Wright was the first to quantify this phenomenon and strongly advocated its potential therapeutic importance. The so-called resolution of the humoralist and cellularist positions by showing their respective roles in the setting of enhanced killing in the presence of opsonins was popularized by Wright after 1903, although Metchnikoff acknowledged the stimulatory capacity of immunosensitized serum on phagotic function in the case of acquired immunity. This attraction was soon proposed to be due to soluble elements released by the bacteria (see Harris for a review of this area up to 1953). Some 85 years after this seminal observation, laboratory studies showed that these elements were low molecular weight (between 150 and 1500 Dalton (unit)s) N-formylated oligopeptides, including the most prominent member of this group, N-formylmethionine-leucyl-phenylalanine, that are made by a variety of replicating gram positive bacteria and gram negative bacteria. Metchnikoff's early observation, then, was the foundation for studies that defined a critical mechanism by which bacteria attract leukocytes to initiate and direct the innate immune response of acute inflammation to sites of host invasion by pathogens. Metchnikoff also self-experimented with cholera that initially supported the probiotic notion. During the 1892 cholera epidemic in France, he was surprised by the fact that the disease affected only some people but not others when they were equally exposed to the infection. To understand the differences in susceptibility to the disease, he drank a sample of cholera but never got sick. He tested on two volunteers of which one was not affected while the other almost died. He hypothesised that the difference in cholera infection was due to differences in intestinal microbes, speculating that those who have plenty of beneficial ones would be healthier. The issues of aging occupied a significant place in Metchnikoff's works. Metchnikoff developed a theory that aging is caused by toxic bacteria in the gut and that lactic acid could prolong life. He attributed the longevity of Bulgarian peasants to their yogurt consumption that contained what was called the Bulgarian bacteria (now called Lactobacillus delbrueckii subsp. bulgaricus). He also espoused the potential life-lengthening properties of lactic acid bacteria such as Lactobacillus delbrueckii subsp. bulgaricus. This concept of probiotics, which he termed "orthobiosis," ==Awards and recognitions==

Metchnikoff won the Karl Ernst von Baer prize in 1867 with Alexander Kovalevsky on the basis of their doctoral research. He shared the Nobel Prize in Physiology or Medicine in 1908 with Paul Ehrlich . He was awarded an honorary degree by the University of Cambridge in Cambridge, UK, and the Copley Medal of the Royal Society in 1906. He was given honorary memberships of the Academy of Medicine in Paris and of the Academy of Sciences and Medicine in Saint Petersburg. • The Odesa I. I. Mechnikov National University operates in Odesa, Ukraine. • The forms part of the National Academy of Medical Sciences of Ukraine. ==Personal life and views==

, Élie Metchnikoff, 1886 Metchnikoff married his first wife, Ludmila Feodorovitch, in 1869. She died from tuberculosis on 20 April 1873. Her death, combined with other problems, caused Metchnikoff to attempt suicide, taking a large dose of opium. In 1875, he married his student Olga Belokopytova. In 1880 Olga suffered from severe typhoid and this led to his second suicide attempt. He was greatly influenced by Charles Darwin's theory of evolution. He first read Fritz Müller's Für Darwin (For Darwin) in Giessen. From this he became a supporter of natural selection and Ernst Haeckel's biogenetic law. His scientific works and theories were inspired by Darwinism. Metchnikoff died in 1916 in Paris from heart failure. According to his will, his body was used for medical research and afterwards cremated in Père Lachaise Cemetery crematorium. His cinerary urn has been placed in the Pasteur Institute library. == Publications ==

Metchnikoff wrote notable books and papers, including: • Leçons sur la pathologie comparée de l’inflammation (1892; Lectures on the Comparative Pathology of Inflammation) • L’Immunité dans les maladies infectieuses (1901; Immunity in Infectious Diseases) • Études sur la nature humaine (1903; The Nature of Man) • Immunity in Infective Diseases (1905) • The New Hygiene: Three Lectures on the Prevention of Infectious Diseases (1906) • The Prolongation of Life: Optimistic Studies (1907) • • • == Explanatory notes ==