READ MOREThat hearty response might have a downside, though. It could play a role in black Americans' higher risk for heart disease, stroke and autoimmune inflammatory diseases, the researchers said.
The findings might lead to treatments that reduce chronic health risks for African-Americans, according to the researchers.
The strength of the immune response was directly related to the percentage of genes derived from African ancestors, said senior researcher Luis Barreiro. He's an assistant professor at the University of Montreal's Department of Pediatrics and researcher at the Sainte-Justine University Hospital Center in Montreal.
"Basically, the more African you have in your genome, the stronger you're going to respond to infection," Barreiro said.
But a strong immune response uses inflammation to attack and defeat infection, he said.
Too much inflammation can cause chronic high blood pressure, damage organs such as the heart, and increase susceptibility for autoimmune diseases such as lupus and Crohn's disease, Barreiro said.
"The immune system of African-Americans responds differently, but we cannot conclude that it is better, since a stronger immune response also has negative effects," he said.
Barreiro and his colleagues from several U.S. universities conducted their study using white blood cells drawn from 175 Americans, 80 of whom were of African descent. In the lab, the researchers infected the white blood cells with listeria and salmonella bacteria, so they could observe the immune response.
After 24 hours of infection, white blood cells from African-Americans killed the bacteria three times faster, the researchers reported.
Genetic differences between blacks and whites due to evolution and natural selection appear to be behind this difference in immune response, Barreiro said. Researchers identified thousands of genes that showed race-based differences in a person's genetic response to infection. ■