The AIDS virus disappeared from the bloodstreams of 10 patients with AIDS or a related disease when they got monthly transfusions of blood plasma from otherwise healthy carriers of the virus, researchers say.

The researchers said the treatment apparently kills the virus without causing serious side effects."It doesn't mean that they don't have any more virus in their bodies," said Dr. Abraham Karpas of the Laboratory of Molecular Biology, affiliated with Cambridge University. "But there is no more free virus in the blood to infect their cells."

The plasma, treated to remove viruses, contains high levels of antibodies that can kill the AIDS virus, Karpas said.

AIDS patients lack such antibodies in their blood, said Karpas, who led the research team. Research details appear in December's issue of The Proceedings of the National Academy of Sciences, a U.S. scientific journal, he said.

Karpas called the results of his study "very encouraging," but other AIDS researchers urged caution in interpreting them.

Dr. Bryan Gazzard of St. Stephen's Hospital in London, where the tests were conducted, said the findings were interesting but that larger trials must be done before anyone could say the treatment offered any clinical benefit.

Dr. James Chin, an epidemiologist with the Geneva-based World Health Organization's Global Program on AIDS, said, "If it's for real, (it) deserves to be further evaluated."

However, "I think that there may be a lot of work between some experimental results like that and what kind of applicability you would have in the real world," he warned in an interview.

"We don't know how effective it would be, how long people would have to take such a product. It could very well be for life. So a lot of things have to be worked out before we can really offer people a real ray of hope," he said.

Acquired immune deficiency syndrome attacks the body's immune system, breaking down its resistance to infection. No cure has been discovered. Not everyone infected with the AIDS virus goes on to develop symptoms.

In trials over the past nine months on six AIDS patients and four suffering from an early stage of AIDS known as AIDS-related complex, the virus in the patients' blood "immediately disappeared . . . following the transfusion of this hyper-immune plasma," Karpas said in an interview.

The researchers said nine of the 10 patients are still alive, reasonably well, and out of hospital nine months later. "Those patients have remained virus negative now for nine months," Karpas said.

Karpas said some of patients in the study with early symptoms of AIDS began producing their own antibodies when injected with the antibody-rich plasma.

"The explanation could be that the neutralizing antibody stopped the virus infecting more T-cells," he said.

T-cells, which are destroyed by the AIDS virus, are a type of blood cell essential to the body's immune defenses.

Karpas said he believes the method could reverse the course of AIDS in some patients, or "at least to keep it at bay."