Mice were immunized with mycoplasma membrane antigen once (day 1) and again 7 days later. Immunized and PBS-inoculated (control) mice from each of the wild-type, IFN-γ−/− and IL-4−/− mice were infected with mycoplasma and 14 days later, lungs were obtained to score the (A) lesion indices, and (B) the numbers of mycoplasma CFUs were determined in lungs and nasal passages. Control mice (grey bar) were not immunized. Immunized mice (black bar) were nasal-pulmonary immunized with mycoplasma antigen alone. This experiment was done twice. Vertical bars and error bars represent mean ×/÷ SE (total n=6). Data were evaluated by ANOVA, followed by Fisher protected least square differences multigroup comparison. “*” denotes significant difference (p ≤ 0.05) from PBS inoculated wild-type mice, “•” denotes significant difference (p ≤ 0.05) from PBS inoculated IFN-γ−/− mice and “■” denotes significant difference (p ≤ 0.05) from PBS inoculated IL-4−/− mice.