(A) The graphs show results of incubating mouse BMCMCs with live PAO1 strain bacteria in ratios of BMCMC:bacteria, ranging from 1:1 to 1:100. PAO1 was not cytotoxic, as reflected by the lack of a change in LDH release from mast cells over the interval of observation. (B) The graphs show results of similar experiments with cells of the human mast cell line LAD-2, which was incubated separately with live and heat-killed Pseudomonas strains PAO1 and PA103, also without significant cytotoxicity or effects on histamine at ratios of mast cells:bacteria, shown in Fig. 1, to stimulate histamine production and release and/or cytotoxicity in neutrophils. Values represent mean ± se; n = 3.