Figure 2. Killing of NTS by blood and serum from Malawian adults and by C9-deficient serum at 45, 90, and 180 minutes.
(A) Killing of 8 invasive Malawian S. Typhimurium isolates by whole blood from a healthy adult Malawian donor. (B) Killing of S. Typhimurium isolate D23580 by whole blood (squares), serum (circles), and blood cells washed in RPMI to remove antibody and complement (triangles). (C) Effect of heat inactivation of serum on ability to kill D23580: fresh serum (circles), heat-inactivated serum (squares), and heat-inactivated serum reconstitution with lyophilized complement (triangles). (D) Inability of C9-deficient serum (triangles) to kill D23580. Killing of Salmonella was enabled by addition of exogenous C9 (squares). (E) Killing of D23580 by fresh and heat-inactivated serum: 100% fresh (triangles); 60% fresh, 40% heat-inactivated (diamonds); 20% fresh, 80% heat-inactivated (squares); 10% fresh, 90% heat-inactivated (circles); and 100% heat-inactivated (x). Negative values correspond with a decrease in viable salmonellae compared with the initial concentration of 106 salmonellae/ml. In A, B, C, and E, data indicate blood and/or serum from 1 healthy adult and are representative of 4 healthy adult donors tested. Where error bars are present, data are mean ± 1 SD of 3 experiments.