Protein’s Role in Lethal Malaria Studied
A natural human protein studied by scientists for years for its possible anti-cancer effect now has been found to play a possible major role in causing a highly lethal form of malaria that affects the brain.
The new information comes from experiments with mouse malaria and from preliminary studies with human malaria.
The finding could lead to the prevention of the brain complication in malaria patients by means of antibodies that block the protein’s destructive effect, according to one of the scientists, Dr. Luis F. Fajardo, a Stanford pathologist and chief of pathology at the Veterans Administration Hospital in Palo Alto.
The experiments were conducted by scientists from a World Health Organization facility in Switzerland and Stanford University.
Causes Many Deaths
The deadly brain complication, known as cerebral malaria, kills an estimated 1 million of the 100 million to 200 million cases of malaria worldwide each year, according to the report in today’s issue of the journal Science.
In the animal experiments, the researchers injected mice with a species of parasite that causes malaria in mice. They noted that the mice that developed cerebral malaria had high levels of the protein, called tumor necrosis factor (TNF).
TNF in their blood was 20 to 35 times higher than the mice that did not develop the brain complication. When they examined the blood vessels in the brains of the afflicted animals, they found that the vessels were clogged by red blood cells and by macrophages, the type of blood cell that makes TNF.
But when the researchers treated other malaria-infected animals with an antibody that blocked TNF activity, the animals did not develop the brain complication and their brain blood vessels were clear.
Possible Connection
Fajardo said “it is very likely” that human cerebral malaria occurs in the same manner and possibly could be prevented by use of antibodies against TNF. Humans with cerebral malaria have been found to have high levels of TNF, he said.
TNF acquired its name in 1962 when a scientist observed that tumors had disappeared in mice with high levels of TNF. Because it was believed that the tumors had been destroyed by TNF, the chemical was called tumor necrosis (killing) factor. Since then, genetic engineering companies have been interested in testing TNF as an experimental anti-cancer agent.
According to Fajardo, TNF is believed to be involved in a wide variety of body functions. It is also known as cachectin, because it causes cachexia, a technical name for the kind of body wasting that occurs in cancer and AIDS patients.
Fajardo said he suspects that TNF may play a role in infectious diseases other than malaria.
