The study’s major findings were as follows: (1) serum S100A8 heterodimer levels were increased in CAP patients upon admission; (2) serum S100A8 heterodimer levels were positively associated with CAP severity scores; and (3) S100A8 knockdown attenuated the inflammatory cytokines induced by Streptococcus pneumoniae infection in human lung epithelial cells. The gene discussed is S100A8; the disease is pneumococcal infection.