Apo-A1 is the major protein component of high-density lipoproteins (HDL), which production occurs in the liver and is gene-determined. HDL is the "healthy" fraction of cholesterol. There is an inverse relationship between HDL and CHD - the higher the HDL, the lower the risk of developing heart disease. 

Apo-A1 has one important and useful function for the body - it activates the LCA enzyme. The enzyme is necessary for macrophage cells not to absorb cholesterol, but to remove it into the vascular bed for further processing by the liver. Thus, the link in the development of atherosclerosis is disrupted, as foam cells are formed from macrophages and subsequently atherosclerotic plaque.

Determination of apo-A1 assay alone is uninformative. It is also necessary to study apo-B to calculate the coefficient of atherogenicity (CA) CA = apo -B/ apo - B1

APOLYPOPROTEIN MEN

• А1 1,04 – 2,02 g/l
• В 0,66 – 1,33 g/l
• В/А (coefficient of atherogenicity) 0,45 – 1,25

WOMEN

• А1 1,08 – 2,25 г/л
• В 0,60 – 1,17 г/л
• В/А (coefficient of atherogenicity) 0,35 – 1,15  

If B/A - more than normal, the risk of atherosclerosis is high, if below normal - low.