These observations are well correlated with the exacerbated pathology found in liver and lung and consequently mortality in Msmeg-PE11-infected mice similar to those observed in a Balb/c mouse model of pulmonary tuberculosis infection where appearance of IL-4 in the lung lesions coincides temporally and spatially with the appearance of areas of pneumonia and necrosis, leading to rapid clinical deterioration and death60. Here, IL4 is linked to susceptibility to pneumonia measurement.