The lungs, spleen and liver of mice were perfused with 10% formalin dissolved in PBS, immersed for 24 h in the same
fixative and paraffin-embedded. Transverse sections, 5 mm, taken via the hilus, were stained with haematoxylin and eosin. Histopathology was performed blind, as the pathologist (H. L.) examined coded slides that did not reveal whether specimens had been collected from controls or from challenged animals. Granuloma was defined as an area of nodular inflammatory lesions that comprised lymphocytes and macrophages