Lifestyle

Antidepressants could boost the immune system, studies found

Antidepressant drugs may have a useful side effect - boosting the immune system, new research has shown.

The pills enhance the activity of natural killer cells - key elements of the immune system.

Evidence suggests they could help the body defend itself against infections such as the Aids virus HIV and even cancer.

Natural killer (NK) cells are white blood cells which home in on infected or cancerous cells in the body. They release agents that cause the cells to self-destruct, so they cease to be a danger.

NK cells are especially active against viruses. Inducing apoptosis, or "cell suicide", causes the invading virus to be destroyed inside the cell. Simply killing the cell by means of a toxic chemical would allow the virus to be released.

Tumours are also targeted by NK cells, as long as they are able to recognise them.

The new research emerged from earlier findings that stress and depression impair NK cell function and can accelerate the progress of HIV/Aids.

Scientists recruited both depressed and non-depressed HIV-positive women and treated them with three different types of drugs used to treat stress and depression.

One was citalopram, a selective seretonin re-uptake inhibitor (SSRI) belonging to the same drug family as Prozac. The other two were the "substance P" antagonist, CP 96,345, and the glucocorticoid antagonist, RU486. Antagonist drugs block specific biological pathways.

The research showed that citalopram and CP 96,345 both increased NK cell activity, while RU486 had no effect.