Macrophages engulf oxidized LDL particles, but not native LDL, because oxidation modifies the apoB protein, activating scavenger receptors.

“so you get advanced in location product issues you get oxidative issues basically what you get is a chemical arrangement mm-hmm that a PO be 100 protein so it's no longer the one that your body synthesized it's recognized as potentially an invading pathogen exactly that's what makes the macrophages the foam cells that's what causes atherosclerosis to begin”

“These guys won the Nobel Prize in 1985 for the LDL receptor discovery and apparently they did some experiments, probably cell culture, where they incubated macrophages with LDL particles. And the macrophages didn't engulf, right? The macrophages don't eat native LDL. They only eat oxidized LDL, probably because either apoB is modified, you know, on the surface, but the scavenger receptor on those macrophages isn't really activated. It doesn't bind to the LDL particle unless they're oxidized.”

“if you give a macrophage a native LDL particle the macrophage is just going to be here floating around like a happy little immune cell it's not going to go over here and eat the sky but if that is oxidized if that has changes to the APO B100 it's going to trigger the scavenger receptor over here on the macrophage it sees it as foreign and it eats it”

“so if the LDL particle is damaged if it's lost electrons if it's become oxidized then you have molecules on the surface of that LDL molecule low density the protein cholesterol a balloon carrying cholesterol and triglycerides that are oxidized they have a free electron they look different and in fact some of the proteins on the outside of the LDL even the APO B100 protein which is sort of identifying it as low density protein cholesterol can look different and they can activate the macrophages to engulf them because they think they're foreign”