Immunomagnetic separation of subpopulations of apolipoprotein A-I.

Mayo Clinic proceedings. Mayo Clinic

PubMedID: 8309265

Rastogi A, Bren ND, Hallaway BJ, Kottke BA. Immunomagnetic separation of subpopulations of apolipoprotein A-I. Mayo Clin Proc. 1994;69(2):137-43.
OBJECTIVE
This study was undertaken to measure the subfractions of high-density lipoprotein (HDL) in patients with diabetes or coronary artery disease and in normal control subjects.

DESIGN
A new immunomagnetic separation technique was used to characterize the lipid profile in four groups: (1) control subjects, (2) patients with diabetes but no coronary artery disease (CAD), (3) those with CAD only, and (4) those with both diabetes and CAD.

MATERIAL AND METHODS
To study the individual roles of the two discrete HDL subpopulations of particles--LpAI/AII (apolipoprotein [apo] A-I associated with A-II) and LpAI (apo A-I without A-II)--in lipoprotein metabolism, we developed an immunomagnetic separation technique using magnetic beads coated with antibodies to human apo A-II. The beads bind particles that contain both apo A-II and apo A-I and are precipitated by a magnetic field. LpAI levels were measured in the supernatant by performing an apo A-I radioimmunoassay. LpAI/AII levels were determined by subtracting the LpAI levels from total plasma apo A-I.

RESULTS
In comparison with control subjects, patients with diabetes, CAD, or both had significantly decreased levels of LpAI/AII. LpAI levels were normal in patients with diabetes without CAD but significantly lower than control values in those with diabetes and CAD.

CONCLUSION
Our findings suggest that both subpopulations of HDL particles have implications in the development of atherosclerosis in patients with and without diabetes.