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Antiphospholipid antibodies in patients with scleroderma: prevalence and clinical significance
  1. G Sanna1,2,3,
  2. M L Bertolaccini1,
  3. A Mameli2,
  4. G R V Hughes1,
  5. M A Khamashta1,
  6. A Mathieu2
  1. 1Lupus Research Unit, The Rayne Institute, King’s College London School of Medicine, St Thomas’ Hospital, London, UK
  2. 2Cattedra di Reumatologia II, Università di Cagliari, Cagliari, Italy
  3. 3Department of Rheumatology, Homerton University NHS Foundation Trust, London, UK
  1. Correspondence to:
    Dr M A Khamashta
    munther.khamashtakcl.ac.uk

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Antiphospholipid antibodies (aPL) are detected in a variety of autoimmune disorders, most commonly systemic lupus erythematosus, but also in some infectious diseases, lymphoproliferative disorders, and even in apparently healthy people.

Although a wide prevalence of aPL in systemic sclerosis has been reported (between 0 and 41%), most studies have focused on anticardiolipin antibodies (aCL) and very little is known about other aPL in this disease. We determined the prevalence and clinical significance of aCL, antibodies to β2-glycoprotein I (anti-β2GPI), and antibodies to phosphatidylserine-prothrombin complex (aPS-PT) in 25 patients with scleroderma (18 with limited and 7 with diffuse scleroderma, as defined by LeRoy et al1) (table 1). Twenty four patients were female (median age 50 years (range 28–70), median disease duration 3 years (range 1–20)). One patient had a history of venous thrombosis. Of the 17 patients who had ever been pregnant, five had an adverse obstetric history. Two patients had miscarriages (before the 10th week of gestation), two patients had a fetal death (at the 10th week of gestation or later), and one patient had a premature birth (before the 34th week of gestation) due to severe pre-eclampsia. Platelet count was normal in all patients. Only one patient had a prolonged activated partial thromboplastin time. One hundred healthy donors with no relevant medical history comprised the control group.

Table 1

 Clinical characteristics of patients with scleroderma*

aCL, anti-β2GPI, and aPS-PT were detected by enzyme linked immunosorbent assay (ELISA).2–4

aPL were present in 8/25 patients. Table 2 shows the distribution of aPL in patients and controls. aCL for IgG/IgM and aCL IgG were more frequently found in patients with scleroderma than in controls (24% v 5%, odds ratio = 6 (1.7–21.7), p = 0.008 and 16% v 3%, odds ratio = 6.1 (1.2–2.9), p = 0.03, respectively). The prevalence of anti-β2GPI did not differ between patients and controls (8% v 3% for IgG/IgM, 4% v 2% for IgG, and 4% v 1% for IgM).

Table 2

 Distribution of aPL in patients with scleroderma and controls

Interestingly, patients with telangiectasia and pulmonary hypertension had IgM aPS-PT more frequently than those without (37.5% v 0%, relative risk = 4.4 (2.0–9.5), p = 0.02 and 66.6% v 4.5%, relative risk = 14.6 (1.8–116.9), p = 0.03, respectively). No associations were found between the other aPL analysed and clinical manifestations of scleroderma.

One patient with scleroderma who had had venous thrombosis also had IgG aCL at low titres. Of the two patients with a history of miscarriages (<10th week of gestation), one had IgG anti-β2GPI and the other IgM aPS-PT. None of the patients who had fetal death (n = 2) or prematurity (n = 1) had aPL.

Although the presence of all aPL was more common in patients with scleroderma than in healthy controls (32% v 5%), the clinical manifestations of antiphospholipid syndrome were not frequently seen in these patients.

The prevalence of aCL in scleroderma has been reported to range from 0%5 to 41%.6 In this study, only one patient had a history of venous thrombosis and aCL at low titres, suggesting that this manifestation may have been aCL related.

Parodi et al described anti-β2GPI in 3/90 (3.3%) patients with scleroderma,7 whereas Schoenroth et al reported a prevalence of 8% when studying 26 patients with this disease.8 These studies are in agreement with our findings.

Although the prevalence of aPS-PT was low in our study, these antibodies were more frequently found in patients with telangiectasia and pulmonary hypertension, supporting the data from Hasegawa et al in their cohort of 112 patients with scleroderma.9 Overall, these findings suggest that aPS-PT may be a marker of vascular involvement in patients with scleroderma. However, as this is a very small study, further research is warranted to confirm or reject this hypothesis.

In summary, aPL are commonly found in patients with scleroderma but the “typical” clinical manifestations of antiphospholipid syndrome are not frequently seen in these patients.

REFERENCES

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