UCLA researchers focused on low-density lipoprotein (LDL), the so-called 'bad' cholesterol. They examined how high levels of oxidized LDL affect bone and whether a type of immune cell called a T-cell plays a role in the process.

Using blood samples from healthy human volunteers, the team isolated the participants' T-cells and cultured them in a dish.

Half of the T-cells were combined with normal LDL - the rest was combined with oxidized LDL. The scientists stimulated half of the T cells to mimic an immune response and left the other half alone.

'Lo and behold, both the resting and the activated T cells started churning out a chemical that stimulates cells whose sole purpose is to destroy bone,' said Effros. Called RANKL, the chemical is involved in immune response and bone physiology.

These findings were published in the PNAS Early Edition online.