Today, a different parasite, Plasmodium falciparum, is the predominant cause of the most fatal form of malaria.
Some laboratory research had shown that the Duffy antigen mops up HIV in the bloodstream, potentially reducing the likelihood that the virus can infect the immune cells that are its primary target.
To explore this possibility, the team studied the medical records and stored blood of 814 black Air Force personnel who were HIV-negative and 470 who were HIV-positive. The fact that all were servicemen eliminated many of the socioeconomic variables that might have confounded the analysis.
Researchers found that airmen without the Duffy antigen were 40% more likely to be infected with HIV -- and if they were infected, they lived longer by an average of two years. That surprised the researchers because typically anything that increases the risk of an infection is also likely to speed the progression of the resulting disease.
David Goldstein, a Duke University population geneticist who studies HIV genetics, said the unusual finding made him hesitant to embrace the result until it could be replicated in other studies -- a task he said he intended to pursue.
Goldstein added that African Americans, the subjects of the study, had an especially diverse genetic heritage that made it more difficult to link a particular gene to HIV susceptibility.
Ahuja said he and his colleagues did not know why the absence of the Duffy antigen increased HIV susceptibility and slowed progression of the disease. One possibility is that people without the Duffy antigen have lower levels of infection-fighting chemokines in their blood.
The lower levels make infection more likely. But once infection occurs, it may limit the amount of inflammation associated with the disease, minimizing damage to the body.
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thomas.maugh@latimes.com
karen.kaplan@latimes.com
