Furthermore, plasma concentration of IL-18 was found to be correlated positively with production of CXCL10, CXCL9, CXCL1, and CXCL8 in SLE patients, it was also shown to be a potent costimulus for the induction of these chemokine release from activated PBMC as there was a significant increase in ex vivo production of these inflammatory chemokines when their PBMC were cultured in the presence of IL-18. This evidence concerns the gene CXCL9 and systemic lupus erythematosus.