Generation of a CD11b/c upregulating and chemotactic factor by hepatocytes of endotoxic rats--nonidentity with...

To further clarify the mechanism of polymorphonuclear leukocyte (PMN) recruitment into the liver associated with short term endotoxin infusion (1), we investigated the effect of a noval factor generated by hepatocytes of such endotoxic rats on the expression of PMN adhesion molecules CD11b/c and chemotactic activity. Conditioned medium of hepatocytes from endotoxin-infused rats shows a fast induction and dose-dependent activity for upregulating CD11b/c expression in and chemotactic activity for blood PMN of naive rats. Supernatants of naive control rats cultured in the presence of endotoxin and Kupffer cells and liver PMNs of endotoxic rats also produce activation, but to a much lesser extent. The upregulating activity can be reduced significantly by heat inactivation at 100 degrees C for 10 min and by pronase hydrolysis at 37 degrees C for 60 min. Generation of the activity does not depend on cyclooxygenase products or phospholipase A2 activity, and it does not seem to be associated with the complement pathway. The activity is associated with molecular masses of 9-12 and 27-32 kDa and cannot be reduced by antiserum to rat interleukin-8 in serial dilutions ranging from 1:50 to 1:25,600. The results show that hepatocytes from acutely endotoxin infused rats generate a small molecular weight protein factor (or factors) that is capable of upregulating PMN 11b/c expression and chemotactic activity and is seemingly different from rat interleukin-8. Thus, hepatocytes in endotoxemia may play an important role in modulating neutrophil function and contributing to the mechanism of neutrophil sequestration into the liver.