Figure 5. Killing of NTS by serum from Malawian children compared with anti-Salmonella IgG and IgM titers and complement C3 and membrane attack complex deposition in vitro killing of S. Typhimurium isolate D23580 by serum at 180 minutes.

(A and B) NTS killing compared with specific anti-Salmonella D23580 IgG (A) and IgM (B) levels. (C and D) NTS killing compared with complement C3 (C) and C5b-9 membrane attack complex (MAC; D) deposition on D23580. The initial concentration was 10⁶ salmonellae/ml. Each point corresponds to serum from 1 child, either less than (filled circle) or more than (open circle) 16 months of age. Numbers at top right denote the number of points in the indicated quadrants, as divided by threshold for normal killing (more or less than 1.5 U Ig, 100 U C3, and 0.6 U C5b-9 membrane attack complex) and normal or impaired killing (more or less, respectively, than 1.2 log₁₀ kill).