APCS and susceptibility to pneumonia measurement: To investigate the effect of SAP deficiency on the inflammatory response to S. pneumoniae pneumonia, the levels of pro-inflammatory cytokines were measured in BALF from wild-type and Apcs−/− mice 4 h and 24 h after i.n. inoculation with 1 × 106 cfu of the S. pneumoniae D39 strain.