Bad News for Protozoa, Fungi and Bacteria

Radioactive particles plus antibodies treat infectious disease

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WEDNESDAY, Aug. 20, 2003 (HealthDayNews) -- In a research first, scientists at Albert Einstein College of Medicine successfully treated an infectious disease by piggy-backing radioactive particles onto antibodies, which zero in on disease-causing microbes without causing harm to healthy cells.

Radioimmunotherapy, which may offer a new way to fight diseases caused by a number of bacteria, fungi, protozoa and other organisms, uses ionizing radiation -- gamma rays or subatomic particles emitted by unstable isotopes. Ionizing radiation is an effective killer of microbes and gamma rays are routinely used to sterilize medical supplies and some foods.

In their study, the researchers affixed isotopes to antibodies and demonstrated that the microbe-killing ability of ionizing radiation can be harnessed for clinical use.

The study appears in the Aug. 18-22 issue of Proceedings of the National Academy of Sciences.

The researchers targeted their radioimmunotherapy against a major fungal pathogen called Cryptococcus neoformans. It can cause potentially fatal encephalitis in people with AIDS and others with weakened immune systems.

Mice were infected with the fungus and, a day later, the researchers injected them with varying concentrations of one or another of antibody preparations containing two different radioisotopes. Some other mice were infected with the fungus but not treated.

The mice treated with either of the radiolabeled antibodies lived much longer than untreated mice and suffered no apparent toxicity from the treatment. The study also found that, 48 hours after treatment, the mice treated with radioimmunotherapy had greatly reduced levels of fungi in their lungs and brains compared with untreated mice.

"These initial studies suggest that radioimmunotherapy could be a useful new antimicrobial weapon, with the potential for killing not only fungi but also other disease-causing microbes while causing few or no side effects," lead author Dr. Ekaterina Dadachova, an assistant professor of nuclear medicine, says in a news release.

More information

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