PON1 and systemic lupus erythematosus: In the controls, PON1 paraoxonase and arylesterase activities correlated only with the concentration of the intermediate HDL (data not shown). PON1 arylesterase activity showed positive associations with the concentrations of all HDL subpopulations, but it was most pronounced with small HDL (r = 0.40204, P = 0.0038) in the SLE group.