The human IL-8 gene promoter does not have CpG island. There are 5 CpG sites in 500 bp upstream of the translation start site. I recommend to using bisulfite sequencing based method, such as bisulfite Pyrosequencing, bisulfite targeted NGS, direct-BSP (Sanger sequencing), or HRM realtime PCR to quantify IL8 methylation. Bisulfite Pyrosequencing is highly recommend in this case.