Background and aims Systemic Lupus Erythematosus (SLE) is considered an independent risk factor for cardiovascular disease. ATP-binding cassette transporter ABCA1, also known as the cholesterol efflux regulator protein, is a ubiquitous cholesterol transporter that is highly expressed in macrophages. Its main function is to donate cholesterol to apolipoproteinA-I in lipid-poor HDL particles. As such, ABCA1 closely influences HDL levels and its role in atherosclerosis has been increasingly studied.

This study was undertaken to determine if antibodies against ABCA1 can be detected in patients with SLE.

Methods Serum from 48 patients were compared with an age and sex-matched control group. Patients were divided in groups A (13 patients) and B (35 patients), respectively with up to 3 and at least 4 SLICC classification criteria (2012). IgG anti-ABCA1 and anti-HDL antibodies were assessed by home-made ELISAs. Plasma lipid profile was determined by standard enzymatic techniques.

Results Group A did not differ from control group. Group B had higher titers of anti-ABCA1 antibodies (p=0.004), with 4 patients showing positive anti-ABCA1 titers (11.4%). In group B, anti-ABCA1 antibodies titers tend to negatively correlate with HDL (p=0.06) and apoliporoteinA-I levels (p=0.04). In both groups, anti-HDL antibodies did not correlate with anti-ABCA1 titers.

Conclusions This is the first report of naturally occurring antibodies against ABCA1. These antibodies are increased in patients with SLE with at least 4 SLICC classification criteria. Future studies will determine their pathogenic role.

This work was supported by the Portuguese Foundation for Science and Technology via the post-doctoral SFRH/BPD/112411/2015 and Fundação Oriente.