In this study, the basal expressions of p38 MAPK in CD4+ T lymphocytes, CD8+ T lymphocytes, and B lymphocytes had been shown to be significantly higher in SLE patients, and the expression of phospho-p38 MAPK in CD4+ T lymphocytes, CD8+ T lymphocytes, and B lymphocytes, and phospho-JNK in CD8+ T lymphocytes and B lymphocytes was also significantly elevated in SLE patients upon the activation by IL-18, exhibiting significant correlation with the plasma concentrations of Th1 chemokine CXCL10. This evidence concerns the gene CD8A and systemic lupus erythematosus.