Cholesterol esterase activity in body fluids.

Antistreptolysin O activity (greater than or equal to 200 Todd units/ml) was found in 20% of 25 ascitic fluids, 20% of 55 pleural fluids and 37-5% of 56 joint fluids. These levels are not due to antibody but to the cholesterol moiety of altered beta-lipoproteins. The activity is precipitable with 10% dextran sulphate. Incubation of mixtures of fluids with titres less than 200 and normal human serum generated eight-fold or greater rises in antistreptolysin titres. This results from the activity of cholesterol esterase in the fluid acting on the beta-lipoprotein of the serum and activity was noted in 90% of ascitic fluids, 59% of pleural fluids and 54% of joint fluids. However, mixtures showing no such rise probably also contain esterase, the failure to demonstrate antistreptolysin activity being due to equilibration of ester derived cholesterol with sub-fractions of high density and very low density lipoproteins.