Surfactant Protein A: regulation of innate and adaptive immune responses in lung inflammation.

The concept that surfactant may have a connection with bone marrow transplant may be startling to many. In fact, the paper by Yang and colleagues (1) provides evidence for such a connection by demonstrating that surfactant protein (SP)-A suppresses the T-cell dependent lung inflammatory response that often occurs in patients (and mice) following allogeneic bone marrow transplant. How is it that surfactant, most widely recognized for its ability to reduce surface tension at the air–liquid interface of the lung, could mediate such a function?