Genetic ancestry and population differences in levels of inflammatory cytokines in women: Role for evolutionary selection and environmental factors
Author summary Individuals of European and African ancestry have different susceptibility for developing specific infections and diseases. Part of this difference in immune response is thought to arise from genetic differences accumulated over the millennia that conferred advantages in fighting different infectious pathogens endemic to different parts of the world. The impact of these immune differences and how they are influenced by modern lifestyles and living environments remains to be understood. Findings from this study revealed population differences in the levels of circulating cytokines, i.e. chemical messengers of the immune system, which were due in part to different demographic and lifestyle factors. Further, a change in the gene encoding for the Duffy antigen receptor protein, identified as rs2814778 and known as the Duffy-null allele, was the most important factor explaining low circulating levels of CCL2 and CCL11, key chemokines regulating the migration of white blood cells, specifically monocytes and eosinophils, which play a role in inflammation. This genetic variant occurs almost exclusively among Africans, likely because of its role in protecting against malaria infection, and results in loss of Duffy antigen protein on red blood cells. The substantial immune differences by ancestry may have broad implications for health disparities.