To further link the observed increased susceptibility of Apcs−/− mice to S. pneumoniae pneumonia to deficiency in SAP, Apcs−/− mice were supplemented by tail vein injection with 5 mg/kg of hSAP 1 h prior to inoculation with D39, and the bacterial cfu in target organs obtained at 24 h. The gene discussed is APCS; the disease is susceptibility to pneumonia measurement.