Elevated serum levels of pro-inflammatory cytokines such as IL-1, IL-6, IL-12, Interferon γ [IFN-γ], chemokines (CCL2, CXCL9, and CXCL10), and transforming growth factor-β were detected in cases infected with SARS with intense illness as compared to persons with simple or mild SARS. This evidence concerns the gene CXCL9 and severe acute respiratory syndrome.