Lungs were obtained from broth-inoculated (uninfected) and mycoplasma-infected wild-type, IFN-γ−/− and IL-4−/− mice, and RNA was isolated. Total RNA was isolated from the lungs of individual mice. Equal amounts of RNA from individual mice (3 or 4 mice/experiment) from each experiment were pooled and used to probe membrane-based cDNA cytokine/chemokine microarrays. Data represent the average value of normalized spot intensities obtained from arrays from 2 different experiments. The results from the RNA obtained from the lungs of mycoplasma-infected wild-type, IFN-γ−/− and IL-4−/− mice were compared to the RNA obtained from the lungs of their respective uninfected counterparts. Scatterplots of gene expression in the lungs of (A) wild-type versus uninfected wild-type mice, (B) infected IFN-γ−/− versus uninfected IFN-γ−/− mice and (C) infected IL-4−/− versus uninfected IL-4−/− mice. A boundary of 2-fold change in either direction was selected. Green plus (+) signs located above the boundary line indicate an increase in gene expression, greater than boundary value, whereas red plus (+) signs below the boundary line indicate a decrease in gene expression. The further the sign is from the 2-fold boundary line, the greater the fold difference. Plus signs within the boundary lines mean the fold change were considered not significant. Each symbol represents one gene. Relative gene expression was plotted as a gradient of colors from light green (minimum expression) to bright red (maximum expression) for uninfected and mycoplasma-infected lungs of (D) IFN-γ−/−, (E) IL-4−/− and (F) wild-type mice. (G) Summary of number of genes changing in the lungs of uninfected IFN-γ−/− and IL-4−/− mice as compared to uninfected wild-type mice. Changes in gene expression are reported only if there was at least an average of ≥ 2-fold difference, with no value of ≤1.5 fold in either individual experiment. Chi square analysis was used to compare the distribution of gene expression changes between groups of mice. There was a significantly different change in the distribution gene expression between wild-type, IFN-γ−/− and IL-4−/− mice (p ≤ 0.001).