SP-B deficiency causes respiratory failure in adult mice

Targeted deletion of the surfactant protein (SP)-B locus in mice causes lethal neonatal respiratory distress. To assess the importance of SP-B for postnatal lung function, compound transgenic mice were generated in which the mouse SP-B cDNA was conditionally expressed under control of exogenous doxycycline in SP-[B.sup.-/-] mice. Doxycycline-regulated expression of SP-B fully corrected lung function in compound SP-[B.sup.-/-] mice and protected mice from respiratory failure at birth. Withdrawal of doxycycline from adult compound SP-[B.sup.-/-] mice resulted in decreased alveolar content of SP-B, causing respiratory failure when SP-B concentration was reduced to transgenic; surfactant proteins B and C; lung; respiratory distress syndrome