Native and reduced-carboxamidomethylated (RCM) HDL3 are incubated with a lipoprotein-depleted plasma fraction in the presence of triacylglycerol-rich particles isolated from Intralipid. Unmodified HDL3 are mainly converted into large HDL2b particles (diameter: 9.84 +/- 0.15 nm); RCM-HDL3 are transformed into both large HDL2b (9.76 +/- 0.10 nm) and small HDL3c (7.68 +/- 0.07 nm). These findings indicate that the apo A-II dimers participate in the remodeling of HDL, by inhibiting the formation of small HDL particles.