A short history of immunology
When plague struck Athens in 430 BC, the historian Thucydides noted that those who had recovered were not attacked a second time and could nurse the sick. The word immunity comes from the Latin immunitas, exemption from duty. In 1796 Edward Jenner used cowpox to prevent smallpox, and in the 1880s Louis Pasteur generalised the method and named it vaccination. In 1890 Emil von Behring and Kitasato Shibasaburō showed that serum "antitoxins" — antibodies — could transfer immunity, while Élie Metchnikoff championed cells that engulf invaders, sparking the humoral-versus-cellular debate. Frank Macfarlane Burnet's clonal selection theory (1957–59) — each lymphocyte recognises one antigen and multiplies when it meets it — became the framework of modern immunology.
Innate and adaptive immunity
Skin, mucous membranes and stomach acid form the first barriers; pathogens that get through meet innate immunity at once. White blood cells such as neutrophils and macrophages engulf them, triggering inflammation. In 1989 Charles Janeway predicted that innate immunity must have receptors for common microbial patterns; the discovery of Toll-like receptors in the 1990s proved him right (Nobel Prize 2011). Dendritic cells, identified by Ralph Steinman in 1973, show fragments of pathogens to T cells and wake adaptive immunity. B cells make antibodies, T cells kill infected cells or direct other immune cells, and some become memory cells that respond faster next time.
| Innate immunity | Adaptive immunity | |
|---|---|---|
| Speed | Minutes to hours | Days to two weeks |
| Key cells | Neutrophils, macrophages, NK cells | T cells, B cells |
| Memory | Little or none | Yes (basis of vaccines) |
When immunity goes wrong — and "boosting" it
Overreaction to harmless pollen or foods causes allergy and other hypersensitivity reactions; attacks on the body's own tissue cause autoimmune diseases such as type 1 diabetes, rheumatoid arthritis and lupus. In 1995 Shimon Sakaguchi identified regulatory T cells that restrain such attacks (Nobel Prize in Physiology or Medicine 2025). A weakened immune system, as with HIV or chemotherapy, lets ordinarily harmless microbes cause infection. Most supplements sold to "boost immunity" lack good evidence, and a stronger response is not always better — balance matters. Evidence supports vaccination, enough sleep, regular exercise, a balanced diet, not smoking and managing stress.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Is there a supplement that reliably boosts immunity?
- Correcting a genuine deficiency, for example in vitamin D or zinc, can help, but there is no solid evidence that supplements boost immunity in people who are not deficient.
- Do vaccines weaken the immune system?
- No. Vaccines train adaptive immunity to remember a pathogen without a real infection, and they do not reduce immunity to other diseases.
Sources reviewed: 2026-10-26
References
- Thucydides. (c. 400 BC). History of the Peloponnesian War, II.51 (on the Plague of Athens).
- Jenner, E. (1798). An Inquiry into the Causes and Effects of the Variolae Vaccinae. London: Sampson Low.
- Behring, E., & Kitasato, S. (1890). Ueber das Zustandekommen der Diphtherie-Immunität und der Tetanus-Immunität bei Thieren. Deutsche Medizinische Wochenschrift, 16, 1113–1114.
- Burnet, F. M. (1959). The Clonal Selection Theory of Acquired Immunity. Cambridge University Press.
- Janeway, C. A. Jr. (1989). Approaching the asymptote? Evolution and revolution in immunology. Cold Spring Harbor Symposia on Quantitative Biology, 54, 1–13.
- Lemaitre, B., et al. (1996). The dorsoventral regulatory gene cassette spätzle/Toll/cactus controls the potent antifungal response in Drosophila adults. Cell, 86(6), 973–983.
- Steinman, R. M., & Cohn, Z. A. (1973). Identification of a novel cell type in peripheral lymphoid organs of mice. Journal of Experimental Medicine, 137(5), 1142–1162.
- Sakaguchi, S., et al. (1995). Immunologic self-tolerance maintained by activated T cells expressing IL-2 receptor α-chains (CD25). Journal of Immunology, 155(3), 1151–1164.
- Murphy, K., & Weaver, C. (2016). Janeway's Immunobiology (9th ed.). Garland Science.