Reduced free protein S levels in patients with inflammatory bowel disease - Prevalence, clinical relevance, and role of anti-protein S antibodies

We evaluated free plasma levels of protein S, a natural anticoagulant facto r, the prevalence of anti-protein S antibodies, a possible cause of protein S deficiency, and their correlation with anti-phospholipid antibodies in 5 3 patients with inflammatory bowel disease (IBD) and 53 age- and sex-matche d controls. Mean free plasma protein S levels (+/- SD) were significantly l ower in IBD patients (0.98 +/- 0.32 IU/ml) than in controls (1.06 +/- 0.28 IU/ml) (P < 0.05); only one patient showed protein S deficiency. Specific a ntibodies to protein S were found in four IBD patients (7.5%) and in one co ntrol(1.9%) (P = NS). Five IBD patients (9.4%) and none of the controls sho wed anti-phospholipid antibodies (P < 0.06). No correlation was found betwe en free protein S levels and anti-protein S antibodies or between anti-prot ein S and anti-phospholipid antibodies. In conclusion, fret: plasma protein S levels are slightly but significantly decreased in IBD patients. The pre valence of anti-protein S and antiphospholipid antibodies is increased in I BD patients. Anti-protein S antibodies do not appear to determine low prote in S levels or to overlap with or belong to anti-phospholipid antibodies.