Pulmonary toxicity in mice after high-dose methotrexate administration with and without leucovorin rescue.

Interstitial lung lesions were induced in mice by high-dose methotrexate with high frequency. They appeared early after treatment; their onset, evolution and recovery parallelled those of lesions to the hemopoietic tissues and the intestine. The pathogenesis of methotrexate lung toxicity in mice is discussed. Leucovorin rescue was ineffective in preventing the lung lesions induced by high-dose methotrexate.