Ultraviolet blood irradiation (UBI) refers to a procedure in which a small volume of a patient’s blood is circulated outside the body, exposed to ultraviolet light, and then returned. The irradiation damages microbial cells and alters immune mediators, and in the early 20th century it was explored as a therapy for infections before modern antibiotics.
Mechanism and historical use
UBI was developed in the 1920s and 1930s based on findings that ultraviolet light can inactivate bacteria and viruses. In the procedure, blood drawn from a patient is passed through a quartz chamber where it is exposed to ultraviolet C light. The energy disrupts nucleic acids and damages microbial membranes, reducing viable pathogens. It also triggers the release of photo-products that modulate leukocyte activity and cytokine production. UBI was trialed for septicemia, pneumonia and tuberculosis in the 1940s, when antibiotics were scarce, and case series reported reductions in fever, improved oxygenation and decreased mortality. With the advent of safe blood transfusion practices and effective antimicrobial agents, the procedure fell out of use. Recent experimental studies have revisited it as a potential adjunct to treat drug-resistant infections and to modulate inflammation, but robust clinical data are lacking.
Clinical reports and considerations
Early reports described the use of UBI to treat bacterial sepsis and viral hepatitis; treated patients often showed transient leukocytosis and symptom improvement, but the studies lacked controls. Modern interest focuses on its immunomodulatory effects rather than direct pathogen killing. Ultraviolet exposure can cause oxidation of plasma proteins, and the procedure carries risks associated with handling and reinfusing blood. Regulatory agencies have not approved it for routine medical use, and it remains an experimental therapy. In summary, UBI is a historically significant technique that exposes blood to ultraviolet light as a means to reduce infectious agents and modulate immune responses. While it stimulated important research into phototherapy and the effects of ultraviolet light on cells, its clinical role today is limited. Related Terms: Ultraviolet Radiation, Phototherapy, Immune Modulation, Blood Irradiation, Photodynamic Therapy