Pulmonary pathology of the motheaten mouse.

Mice, homozygous for the motheaten gene, developed an unusual pneumonia that was the cause of natural death of mice by 7 weeks of age. Initial lesions consisted of focal accumulations of alveolar macrophages in alveoli, especially adjacent ot bronchioles. Needle-like crystals formed in lysosomes of macrophages and numerous macrophages with crystals filled most alveoli in 5- to 7-week-old mice. Although motheaten mice had lesions in other tissues and were shown by other investigators to have immunological defects, the unusual pneumonia was the only lesion severe enough to cause death.