APT070 inhibits complement activation during in vitro cardiopulmonary bypass.

BACKGROUND: The proteins of the complement cascade play an important role in inflammation and the immune response. They have been shown to be activated during cardiopulmonary bypass (CPB), and may be responsible for the inflammatory response to CPB. We looked at the effect of APT070, an anti-complement agent, on human blood during in vitro CPB. MATERIALS AND METHODS: Four hundred millilitres of blood was venesected from healthy human volunteers and heparinised. To the blood was added either APT070 to a concentration of 50 microg/ml (n=5) or vehicle control (n=4). The blood was entered into an in vitro CPB circuit and circulated for 90 min. RESULTS: Our results showed that after 90 min of in vitro bypass APT070 significantly inhibited the activation of compliment as demonstrated by C3a (p=0.03) and sC5b-9 (p=0.01) levels, and reduced neutrophil stimulation as measured by CD11b expression (p=0.04 at 90 min). CONCLUSION: APT070 significantly inhibits complement and neutrophil activation. This result may have considerable implications, especially if it can be shown to decrease the inflammatory sequelae of CPB.