[Serum amyloid A apolipoprotein (apo SAA). Implications in inflammation and in lipoprotein modifications]

The measurement of serum amyloid A apolipoprotein (apo SAA) during acute phase inflammation offers a high interest because of its specificity, sensitivity and early increase of its levels, compared to other acute phase proteins. Furthermore apo SAA is transported in serum in association with lipoproteins, in particular with their denser subpopulation, HDL3 thus inducing their modification. The decrease in Lp AI:AII concentrations in inflammatory diseases is the consequence of the decrease in HDL3. In general the HDL3 composition was changed with a displacement of apo AI by SAA. Another interest to this protein is its relationship with amyloidosis. Apo SAA is the presumed precursor of amyloid A protein, which can be deposited in various tissues, leading to secondary amyloidosis.