Extracorporeal photopheresis is a process in which blood is drawn from a patient who has been given 8-methoxypsoralen, a light-activated photosensitising drug that is thought to bind to DNA. The red and white blood cells are separated and the white cells are passed through a sterile chamber and irradiated with ultra-violet light, then returned to the body. Approximately one-third of the individual’s white blood cells are treated in this way.

It is unclear why this might be beneficial for people with HIV. It is thought that the process may cause the drug to bind to and inactivate HIV. The treatment may also damage HIV-infected cells, making it easier for the immune system to recognise and respond to viral proteins.

Extracorporeal photopheresis is an approved treatment in the United States for cutaneous T-cell lymphoma, a tumour of the CD4 cells. A variation of the technique is used at some British specialist centres as a treatment for psoriasis. The drug is obtained on a named patient basis and given by injection, before the patient has a session on a sun bed to activate the drug in the skin.

As an HIV treatment, it is an unlicensed, experimental procedure. It has been studied in small, uncontrolled trials among people with AIDS, but no clear effects on markers such as CD4 cell count or antibody levels were seen. However, several participants reported improvements in mild symptoms such as swollen lymph nodes, fever and night sweats^[1][2]. No side-effects were seen.

Ultra-violet irradiation can have side-effects including burning, development of eye cataracts, accelerated aging and the development of skin cancer. Ultra-violet light has also been shown to stimulate HIV replication in test-tube studies, but the only study in which HIV viral load was measured in people receiving ultra-violet radiation found no evidence of an increase in viral replication.

No studies of extracorporeal photopheresis are taking place in the United Kingdom and the treatment is not known to be available to people with HIV through other means.