Trauma, high density lipoproteins, and serum amyloid protein A

Several apoproteins not readily detectable in normal serum lipoproteins were found in markedly increased amounts in the lipoprotein density interval 1.125-1.21 g/ml (HDL3) of serum obtained from victims of severe trauma. Following electrophoretic separations, they were shown to be isotypes of the acute-phase protein serum amyloid A (SAA) by immunoreaction with antiserum to the structurally related tissue amyloid protein A (AA). The two principal apoSAA isotypes in the HDL3 of trauma patients appear to be identical to the two principal isotypes (apoSAA1 and apoSAA2) previously isolated from the HDL3 of pooled serum representing an unselected patient population. Concentrations of apolipoproteins A-I and A-II in the HDL3 of the trauma patients were significantly lower than in the HDL3 of normal serum. Evidence is presented that several recently described 'new' families of HDL apoproteins, all of an acute-phase nature, are SAA apoproteins, which are emerging as sensitive indicators of tissue damage.