VARIABILITY OVER TIME OF COMPLEMENT ACTIVATION INDUCED BY AIR BUBBLESIN HUMAN AND RABBIT SERA

Complement activation induced by air bubbles in rabbit and human sera was studied by measuring the generation of anaphylatoxin des-Arg-C5a. des-Arg-C5a was quantified by sandwich enzyme-linked immunosorbent ass ays based on neoepitope-specific anti-des-Arg-C5a monoclonal antibodie s. Air bubbles were continuously introduced to serum via a calibrated microflowmeter, and the serum was incubated at 37-degrees-C for 30 min . Air bubbles clearly generated increased amounts of des-Arg-C5a compa red with corresponding levels in control serum, and a dose-dependent, effect was also noted. Strong positive correlations between des-Arg-C5 a concentrations in control sera and sera incubated with air bubbles a t a flow of 0.5 ml/min were found. To study variation over time, serum was obtained at regular intervals from six rabbits and from six healt hy humans during 66- and 196-day periods, respectively. A pronounced i ntraindividual variability over time was thus observed. The reason for the large variability is at present unknown. We conclude that the sen sitivity of complement to activation by air bubbles is not an inherent , static feature of the complement system of an individual. Therefore single-point analysis of complement activation by air bubbles appears to be an inappropriate parameter bv which to differentiate a ''sensiti ve'' or ''insensitive'' complement system between individuals.