Figure 2. Requirement for IL-4 but not IFNγ in production of PA-neutralizing IgG.

A Sera from experiment in Figure 1 were tested for their ability to protect RAW267.4 macrophages from LT toxicity. Graph shows neutralization by sera from C57Bl/6 mice, IL-4^−/− and IFNγ^−/− mice. Each data point represents an individual mouse and the mean survival of the cell line following treatment with LT and sera is indicated. B Mice were challenged with LT as indicated. C Pooled sera from naïve (n = 5) and PA-immunized (n = 5) mice were transferred to naïve IL-4^−/− mice before challenge with LT. Three and four IL-4^−/− mice per group received naïve and immune sera respectively. Data in A and B are representative of two independent experiments while data in C are from a single experiment. Graphs show percent survival following LT administration. Statistical significance (p<0.05) is indicated by asterisks.