INJECTING ONE WART WITH IMMUNE-TESTING AGENT: STUDY

TORONTO (CP) - Skin injections to test a person's immune response, similar to what doctors use to check for allergies, can get rid of unsightly warts - and not just one, but up to hundreds at a time by treating just a single bump, a study shows.

Researchers at the University of Arkansas for Medical Sciences injected warts with substances used to test a person's immunity to mumps, candida and trichophyton (the fungus that causes athlete's foot). None of the preparations, called skin test antigens, contain live infectious agents, so they can't cause disease.

Sixty per cent of those injected with the antigens saw their treated warts disappear, while about half of those with multiple lesions on their bodies ended up entirely wart-free, said lead researcher Dr. Thomas Horn, head of dermatology at the university.

That's because the injection pricks the immune system into mounting a defence against the mumps, candida (a yeast) and the trichophyton fungus - and at the same time stirs up white blood cells (lymphocytes) to take care of the human papilloma virus, the agent that causes warts.

"So while the body is initially responding to, let's say, candida, the body's immunologic repertoire is broad enough that there are lymphocytes in that mix that say: 'Let's do something about the wart virus'.

"So one of the joys of this is that patients with a large wart or patients with multiple warts, we only need to treat one of several to get many to go away, and in some cases hundreds."

The study, published in this week's Archives of Dermatology, involved 201 patients. About half had their warts treated with antigens, while the other half received injections of saline or interferon, a protein produced by cells that helps regulate the body's immune system. Patients in the antigen group had a significantly higher immune-system response rate.

The method works on all kinds of warts, from the familiar raised type found on the face, hands and soles of the feet, to flat warts, the type spread by shaving on areas like a man's face or a woman's legs.

Side-effects, including redness and soreness at the injection site and fever, were relatively rare and mild, Horn said.

Most current treatments try to destroy the wart by cutting it out, freezing it with liquid nitrogen or zapping it with a laser - methods that can be somewhat painful, especially in tender areas like the foot bottom (plantar warts) or around the fingernails.

"The nice thing about this is we treat two per cent of the surface area of the wart and we get the whole thing to go away," said Horn, noting that he's seen warts as big as saucers.

"This should become a standard treatment for warts . . . a routine treatment in our box of tools for patients with warts, whether that's a patient with a single wart or patients with multiple warts," said Horn. "It is effective, safe and relatively painless."

But Dr. Neil Shear, head of dermatology at Toronto's Sunnybrook and Women's Health Sciences Centre, said that when it comes to single warts, there are much easier ways of removal than giving patients - especially children - an injection.

Among those treatments is, of all things, duct tape. Doctors cover the wart for six days with the silver tape, then "pumice down" the dead skin on the seventh, he said. "It's easy, it works and you can do it at home."

However, Shear called the potential of eradicating numerous warts at one time "exciting. None of the other treatments we use right now really do that.

"Warts are funny creatures, and even though they're probably the most common chronic viral infection that humans have, we still haven't got very good at getting rid of them. And they're a big problem.

"Some people get a wart here and there, but some people just don't seem to fight it, their immunity is not up to snuff and they end up with quite large warts."

Still, Horn's research may have implications beyond the merely cosmetic.

The human papilloma virus is also the culprit behind genital warts, a common cause of cervical cancer.

With other research by his team being considered for publication, Horn would say only that they "have data to show that this treatment works for genital warts."

"The study that we would like to do is a long-term study in which we treat genital warts and follow women's pap smears (tests for cervical cancer)," he said.

There are dozens of strains of human papilloma virus, and the one that causes genital warts probably differs from those that cause typical warts - although even a few of those may lead to skin cancer, said Shear.

But he lauds any research that advances knowledge of this common, easily transmitted family of viruses.

"The human papilloma virus is a potentially serious infection, so it's nice to see that people are doing novel work...stimulating the body's own defence system to try to clean them up."