People with infections, such as syphilis, will make antibody directed against the phospholipids surrounding the cell. But, people with APS make antibodies directed against the b 2-glycoprotein 1, which binds to the phospholipid. Lupus is more frequent in African Americans than Caucasians. However, APS is seen more in Caucasians and Asians. The antibody may be in the blood stream for years before you see anything.
Some people live a lifetime with the antibodies and show no symptoms.
One theory is that the antibody itself irritates the blood vessels. When cells are irritated, phospholipids flip from the inside to the outside. Another theory is that an infection triggers the lipids on the inside to flip to the outside of the cell membrane and trap the antibody. We know that the antibody runs in families. It is also known that women more than men have the antibody.