Frequency of antibodies to the cholesterol transport protein apolipoprotein A1 in patients with SLE

In examining reasons for premature atherosclerosis in systemic lupus erythematosus (SLE), we previously reported low levels of the cholesterol transport protein apolipoprotein Al (apoAl) in these patients, and specific antibodies to purified apoAl were identified in the sera of 5 out of 30 lupus patients. The current study was initiated to determine whether these antibodies are common in lupus patients. 520 serum samples from 175 patients with SLE or primary antiphospholipid syndrome (PAPS) were tested for antibodies to purified apoAl. Positive sera were retested for binding to apolipoprotein incorporated into reconstructed nascent or mature high-density lipoprotein (HDL). Autoantibodies tc, apoAl were found in 32.5% of patients with SLE and 22.9% of patients with PAPS, associated with the presence of aPL (anti-beta(2) glycoprotein-1, anti beta(2) GPl) antibodies. When reconstructed, nascent and nature HDL molecules were compared as antigen-containing environments, positive sera reacted best to apoAl embedded in mature HDL molecules. This report confirms the high prevalence of antibodies to apoAl in patients with systemic lupus and suggests a high affinity of these antibodies for mature HDL.