Levels Of Antibodies At Liver Stage May Predict Resistance To Disease.(Brief Article)

2001 DEC 5 - (NewsRx.com & NewsRx.net) -- High levels of antibodies against the liver stage of the malaria parasite appear to predict resistance to the disease say researchers from Brown University and the Seattle Biomedical Research Institute.

These findings could eventually lead to new strategies for malaria vaccines or treatments.

"Malaria occurs in stages in the human body," says Jonathan Kurtis, assistant professor of pathology and laboratory medicine at Brown University, and the lead author of the study. "In the first stage a low number of parasites invades the liver. This liver stage is not harmful. It's the second stage, the blood stage, where the clinical disease we know as malaria occurs."

Proteins, known as antigens, that elicit immune responses are present in the material surrounding the parasite during the liver stage. These liver stage antigens (LSAs) are thought to stimulate resistance to develop against infection with the parasite. The first LSA (LSA-1) to be identified was isolated using antibodies from a man who was immune to the liver stage but not the bloodstage of the parasite - a result of taking chloroquine for years while living in a malaria endemic area.

Kurtis and his colleagues at the Walter Reed Project in Kenya hypothesized that a strong antibody response to LSA-1 might be associated with high levels of resistance to malaria. To test this hypothesis they treated males in Kenya with antimalarial drugs to clear any existing infection and after two weeks tested their blood for the presence of antibodies. They then monitored the men for 20 weeks, testing their blood at regular intervals for malaria parasites. The data showed a relationship between antibody levels and infection.

"If you were one of the lucky few to have a high level of antibodies to ...