Ethnic differences in plasma levels of interleukin-8 (IL-8) and granulocyte colony stimulating factor (G-CSF)

Ethnic neutropenia is common in people of African descent. As interleukin-8 (IL-8) and granulocyte colony stimulating factor (G-CSF) bind to receptors on neutrophils, ethnic differences in neutrophil counts are hypothesized to result in different plasma levels of these cytokines. A prospective study was conducted in 72 healthy young volunteers. Neutrophil counts were 60% higher in Caucasians (P<0.00001). Average IL-8 and G-CSF levels were about 50% and 70% higher in African volunteers compared with Caucasian volunteers (P=0.0008 and P=0.00005, respectively). Additionally, oxidative burst capacity in stimulated neutrophils was significantly lower in volunteers of African descent (P=0.03 between both groups). In sum, lower neutrophil counts are associated with higher levels of IL-8 and G-CSF in Africans.