Any science teachers, please help! Need help understanding atherosclerosis?

Hi there. I've read nearly everything on atherosclerosis. I'm so confused as to why white blood cells can't fulfil their role in neutralising the cholestrol and other fatty materials at the sites of artery damage. Why do they just turn into foam cells and lie under the arteries? Is it some kind of chemical reaction that hinders their finction? Any info appreciated. I don't think any websites will help, they are so complex, i just need a simple explanation so i can get a basic grasp of what the problem is with these white blood cells :)

Damaged tissue releases chemicals that attract white blood cells, which then attack microorganisms and consume damaged cells.

In atherosclerosis white blood cells鈥攎onocytes and lymphocytes鈥攊nteract with the endothelium, which is the cell layer of the blood vessel wall that faces the blood stream.

Following adherence of these white blood cells to the endothelium, they migrate across the endothelium and into the arterial wall. Once trapped in the arterial wall, the monocytes engorge oxidized (鈥渂ad鈥? cholesterol and are converted into fat-laden foam cells.

Formation and aggregation of foam cells is the first manifestation of atherosclerosis, leading to the narrowing of the opening of the artery and, eventually, to full-blown CVD.

Hope this makes it a bit clearer :)

The white blood cells (macrophages) almost become 'trapped' in the artery due to 'chemotactic cytokines' released by the oxidised LDLs already residing the artery wall. These 'chemotactic cytokines' are chemical messengers attracting the white cells to invade the artery and engulf the oxidised LDL, thereby initiating the atherosclerosis.

The oxidised LDL also generates adhesion molecules causing the white cells to stick to the blood vessel. The white cells when inside the blood vessel wall then uptake large amounts of oxidised LDL in an unregulated fashion because of the 'modified' nature of the oxidised LDL.