Antibody against human lipoprotein lipase

A polyclonal antibody against human lipoprotein lipase (LPL) was prepared. LPL from post-heparin plasma was first purified by heparin Sepharose 4B affinity chromatography. Protein impurities co-eluted with LPL were then eliminated by electrophoresis in the presence of ampholytes. Antithrombin III was identified in this fraction of protein impurities by immunodiffusion against a human antithrombin antiserum, while no antithrombin III could be detected in the purified LPL fraction. Immunodiffusion revealed a single line of precipitation between this antibody and human post-heparin plasma LPL. When pre-incubated with a constant activity of highly purified post-heparin plasma LPL (2.7 mU/75 microliters), an equal volume of the anti-LPL antiserum, either pure or diluted to 1/32 caused complete inhibition of the enzyme activity. Half maximal inhibition was observed at a dilution of approximately 1/200. By using a secondary antibody, it was shown that antiserum inhibited LPL activity by means of its immunoglobulins. This antibody was able to inhibit LPL from human adipose tissue, indicating that human LPL released from endothelial cell membranes has common antigenic determinants with adipose tissue LPL.