RESUMO
Clinical and experimental gerontologists are extremely interested in lipoproteins as well as in new methods for investigating and probing the apolipoprotein pattern. Using immunofixation electrophoresis, we separated free apolipoprotein A-1 from the apo A-1 associated with high-density lipoproteins. Free apolipoprotein A-1 is a low-molecular-mass form of apo A-1 that seems to contain an extremely low quantity of lipids. The use of IFE as a tool for probing free apo A-1 has revealed new and interesting findings, such as its "artificial" increase during serum conservation at temperatures between 0-4 degrees C. From the clinical point of view, we demonstrated a decrease to the point of disappearance of free apo A-1 in some patients with liver cirrhosis. Moreover, one of the main findings here reported is the failure of anti-human apo A-1 murine monoclonal antibody and monoclonal antibody mixture to precipitate free apo A-1 in agarose systems. This discovery has important implications both for basic knowledge on apolipoproteins and for practical reasons concerning variability in those immunoassays (radial immunodiffusion) utilizing monoclonal antibody mixtures.