May 15, 2025 marks the 180th anniversary of the birth of the world-famous scientist Ilya Ilyich Mechnikov, who was awarded the Nobel Prize in Physiology and Medicine in 1908 (jointly with P. Ehrlich) for his research into the nature of immunity. I. Mechnikov is an outstanding scientist, the founder of the theory of immunity (phagocytic theory) and evolutionary embryology. His main scientific achievements include the discovery of the phenomenon of phagocytosis, the creation of the first school of microbiologists and immunologists, and the development of the doctrine of probiotics. І. Mechnikov also introduced the term «gerontology» and studied the issue of longevity, and his scientific works are highly valued all over the world.

The article mainly analyzes the scientific works of I. Mechnikov in the fields of medicine and biology. During the years 1866–1886, the scientist was engaged in the development of issues of evolutionary and comparative embryology. Together with A. Kovalevsky, he is considered the founder of this direction. I. Mechnikov discovered the phenomenon of phagocytosis in 1882, which means the process by which cells absorb and digest foreign particles, such as bacteria and viruses. Based on this discovery, he developed the phagocytic theory of immunity in 1883, which became the foundation for cellular immunology. His work in the field of immunity, as well as research on aging and microbiology, brought him the Nobel Prize in Physiology and Medicine in 1908. I. Mechnikov is a Nobel laureate and the author of the theory of the origin of multicellular animals, in other words, the phagocyte theory. In 1882, he discovered a new phenomenon for science – phagocytosis. He announced this discovery a year later at the VII Congress of Physicians and Naturalists in Odessa. Later, in 1892, on the basis of phagocytosis, he would develop the pathology of inflammation. Ilya Ilyich also made a huge leap in science – he created the phagocytic theory of immunity. The scientist described it in his work «Immunity in Infectious Diseases» in 1901. Most of Mechnikov's works on bacteriology are devoted to the study of the epidemiology of cholera, tuberculosis, typhoid fever and other diseases.

1. Gaysinovich, A. E. (1974). Mechnikov Ilya Ilich [Mechnikov Ilya Ilyich]. In: Bolshaya sovetskaya entsiklopediya v 30 t. – Great Soviet Encyclopedia in 30 volumes. Moskva, Vol. 16 [In Russian].
2. Bachynska, O. A. (2009). Mechnykov Illia Illich [Mechnikov Ilya Ilyich]. In: Entsyklopediia istorii Ukrainy u 10 t. – Encyclopedia of the History of Ukraine in 10 volumes. Kyiv: Nauk. dumka, Vol. 6. La-Mi, p. 631 [In Ukrainian].
3. Skrypal, I. H. (2018). Mechnykov Illia Illich [Mechnikov Ilya Ilyich]. In: Instytut entsyklopedychnykh doslidzhen NAN Ukrainy – Institute of Encyclopedic Research of the National Academy of Sciences of Ukraine. Vol. 20, p. 136 [In Ukrainian].
4. Pavlovskiy, E. N. (1952). I. I. Mechnikov i Voenno-meditsinskaya akademiya [I. I. Mechnikov and the Military Medical Academy]. Trudyi instituta istorii estestvoznaniya – Proceedings of the Institute of the History of Natural Science, 4, 325–331 [In Russian].
5. Verhunov, V. A. (2008). Ukraina ta Frantsiia u zhytti ta tvorchomu dorobku nobelivskoho laureata I. I. Mechnykova (1845–1916): nevidoma arkhivna storinka istorii vitchyznianoi ahrobiolohii [Ukraine and France in the life and creative work of Nobel laureate I. I. Mechnikov (1845–1916): an unknown archival page in the history of domestic agrobiology]. Silskohospodarska mikrobiolohiia: Mizhvid. temat. nauk. zb. – Agricultural microbiology: Interdisciplinary thematic scientific collection. Chernihiv, vol.8, (pp. 168–177) [In Ukrainian].
6. Telepnova, L. G. (2013). Mechnikov I. I. – pervyiy nobelevskiy laureat Ukrainyi [I. I. Mechnikov – Ukraine's first Nobel laureate]. Kraevedcheskie chteniya – Local history readings. Harkov, (pp. 7–9) [In Russian].
7. Palamarchuk, N. I. (2015). Illia Mechnykov – laureat Nobelivskoi premii, urodzhenets Ukrainy [Ilya Mechnikov – Nobel Prize laureate, born in Ukraine]. Storinky istorii – Pages of history, 39, 33–41 [In Ukrainian].
8. Turovska, L. (2025). «Svitiachy inshym, zghoraiu sam». 180 rokiv vid dnia narodzhennia Illi Illicha Mechnykova [«Shining for others, I burn myself». 180th anniversary of the birth of Ilya Ilyich Mechnikov]. Nauka i suspilstvo – Science and society, 5, 36–39 [In Ukrainian].
9. Mechnikova, O. N. (1926). Zhizn Ili Ilicha Mechnikova [The Life of Ilya Ilyich Mechnikov]. Moskva; Leningrad [In Russian].
10. Reznik, S. E. (1973). Mechnikov [Mechnikov]. Moskva [In Russian].
11. Blinki, E. A. (1972). I. I. Mechnikov [I. I. Mechnikov]. Moskva [In Russian].
12. Mechnikov, I. I. (1926). Stranitsyi vospominaniy. Sbornik avtobiograficheskih stattey [Pages of Memories. A collection of autobiographical articles]. Moskva [In Russian].