Heparin increases HLA-G levels in primary antiphospholipid syndrome.
OBJECTIVE
The aim of this study was to investigate the HLA-G serum levels in Primary Antiphospholipid Syndrome (PAPS) patients, its impact on clinical and laboratory findings, and heparin treatment.


METHODS
Forty-four PAPS patients were age and gender matched with 43 controls. HLA-G serum levels were measured using an enzyme-linked immunosorbent assay (ELISA).


RESULTS
An increase in soluble HLA-G levels was found in patients compared to controls (3.35 (0-22.9) versus 1.1 (0-14), P = 0.017). There were no significant differences in HLA-G levels between patients with and without obstetric events, arterial thrombosis, venous thrombosis, or stroke. Sixty-six percent of patients were being treated with heparin. Interestingly, patients treated with heparin had higher HLA-G levels than ones who were not treated with this medication (5 (0-22.9) versus 1.8 (0-16) ng/mL, P = 0.038). Furthermore, patients on heparin who experienced obstetric events had a trend to increased HLA-G levels compared to patients who were not on heparin and did not have obstetric events (5.8 (0-22.9) versus 2 (0-15.2) ng/mL, P = 0.05).


CONCLUSIONS
This is the first study to demonstrate that serum HLA-G levels are increased in APS patients. We also demonstrated that heparin increases HLA-G levels and may increase tolerance towards autoantigens.
Reumatologia Divisão, Faculdade de Medicina, Universidade de São Paulo, Sala 3105, Avenida Dr. Arnaldo, 455, 01246-903 São Paulo, SP, Brazil.
Jozélio Freire
JF
de Carvalho
Ricardo M
RM
de Oliveira
Carlos Ewerton Maia
CE
Rodrigues
Andréa
A
Glezer
Eloísa
E
Bonfá
Rosa Maria Rodrigues
RM
Pereira
D000328:Adult; D016736:Antiphospholipid Syndrome / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D059951:HLA-G Antigens / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics; D006493:Heparin / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged
D059951:HLA-G Antigens; D006493:Heparin