Is plasma HDL concentration rate-limiting for reverse cholesterol transport?

Plasma high-density lipoprotein HDL) concentration is a major risk factor for atherosclerosis in humans, and there is strong experimental evidence that HDLs and apolipoprotein (apo) A-I retard atherogenesis in animals. Although it is well-established that HDLs play a central role in reverse cholesterol transport, it is not yet clear that this explains their antiatherogenic activity. Although plasma HDL concentration can be rate-limiting for cholesterol efflux from cultured cells, more work is needed to determine whether or not this is also true in vivo.