In-vitro activation of complement system by lactic acidosis in newborn andadults

INTRODUCTION: Complement activation occurs secondary to a variety of extern al stimuli. Lactic acidosis has been previously shown to activate the compl ement factors C3a and C5a. In the present investigation we examined the dif ferential effect of lactic acidosis on anaphylatoxin levels in cord and adu lt blood. Furthermore we aimed to determine if the entire complement cascad e could be activated by lactic acidosis. Methods: Cord and adult blood samples (n = 20 each) were collected and incu bated for one hour in either untreated condition or with the addition of la ctate in two concentrations (5.5 mmol/l vs 22 mmol/l). Following incubation , levels of C3a, C5a and sC5b-9, and blood gas parameters were determined. Results: Anaphylatoxin (C3a and C5a) and sC5b-9 levels increased with the a ddition of lactate in a dose-dependent manner in cord and adult blood (C3a: 1 h, 5.5 mmol/l, 22 mmol/l: 418/498/622 mug/l in cord blood; 1010/1056/138 1 mug/l in adult blood, p<0,05; similar results were found for C5a and sC5b -9). Conclusion: Lactic acidosis leads to an activation of the entire complement system in neonates and in adults. This activation is dose-dependent and mo re pronounced in adults as compared to neonates.