Cytokine generation in rabbits during extracorporeal lung assist with a mini hollow fiber lung

To examine host responses to extracorporeal lung assist (ECLA) in small animals, we developed a mini hollow fiber lung of nonmicroporous polyolefin and an extracorporeal bypass circuit with a priming volume of 25 ml. This circuit allowed ECLA of up to 72 h without blood transfusion in 20 rabbits. The ECLA procedure induced the appearance of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) receptor antagonist (IL-1Ra) in plasma, but not IL-1 beta. However, these changes were observed only at the initial stage of ECLA, and the levels returned to pre-ECLA levels within 24 h. Although leukocytes adhering to the hollow fibers were immunohisto-chemically positive for IL-1 beta and IL-Ra, the plasma levels of these cytokines in response to ECLA were not different from those observed in rabbits given anesthesia and subjected to minor surgery but without ECLA. Thus, ECLA itself is a minor factor in the production of these cytokines.