The G-protein-coupled receptor, CXCR4, is highly expressed on a number of cell 
types, and together with its ligand, CXCL12, plays an important role in immune 
development and trafficking of cells. CXCR4 promotes tumor growth, angiogenesis 
and metastasis, and is a prognostic marker in a number of different types of 
tumors. Additionally, CXCR4 is utilized, together with CD4, for entry of 
T-tropic HIV viruses. Ethnic differences in incidence and mortality of various 
cancers, and in the response to highly active antiretroviral treatment (HAART) 
of HIV-1 infected individuals have been reported. The aim of this study was to 
establish if differences in the CXCR4-CXCL12 axis exist between ethnically 
divergent uninfected South Africans. CXCR4 density was significantly higher on 
CD4(+) and CD8(+) T cells, B cells and CD56(dim) NK cells, and CXCL12 levels 
lower in Black compared with Caucasian individuals. Furthermore, an inverse 
correlation was observed between CXCR4 density on CD56(+) and CD3(+) cells and 
age, only in Black individuals. CXCL12-3'A heterozygosity (AG) found in 28% of 
Caucasians did not explain the higher plasma levels of CXCL12 compared to Black 
individuals who were all GG genotypes, suggesting that other factors influence 
homeostatic levels of CXCL12. In conclusion, this study demonstrates that 
ethnically divergent populations show clear differences in both CXCR4 density 
and CXCL12 plasma levels which may influence the course of cancer and HIV-1 
infection.