Anti-phospholipid antibodies restore mesenteric ischemia/reperfusion-induced injury in complement receptor 2/complement receptor 1-deficient mice

Complement receptor 2-deficient (Cr2(-/-)) mice are resistant to mesenteric ischemia/reperfusion (I/R) injury because they lack a component of the natural Ab repertoire. Neither the nature of the Abs that are involved in I/R injury nor the composition of the target Ag, to which recognition is lacking in Cr2(-/-) mice, is known. Because anti-phospholipid Abs have been shown to mediate fetal growth retardation and loss when injected into pregnant mice, we performed experiments to determine whether anti-phospholipid Abs can also reconstitute I/R injury and, therefore, represent members of the injury-inducing repertoire that is missing in Cr2(-/-) mice. We demonstrate that both murine and human monoclonal and polyclonal Abs against negatively charged phospholipids can reconstitute mesenteric I/R-induced intestinal and lung tissue damage in Cr2(-/-) mice. In addition, Abs against beta2 glycoprotein I restore local and remote tissue damage in the Cr2(-/-) mice. Unlike Cr2(-/-) mice, reconstitution of I/R tissue damage in the injury-resistant Rag-1(-/-) mouse required the infusion of both anti-beta2-glycoprotein I and anti-phospholipid Ab. We conclude that anti-phospholipid Abs can bind to tissues subjected to I/R insult and mediate tissue damage.

Thrombosis and antiphospholipid syndrome: a preliminary assessment of three antithrombotic treatments

To assess retrospectively three antithrombotic treatments in the secondary prevention of thrombosis in the antiphospholipid syndrome (APS), 23 patients (six systemic lupus erythematosus, seven lupus-like disease and 10 primary antiphospholipid syndrome) were included in this study. Treatments assessed were: (1) aspirin 75 mg daily, (2) warfarin (international normalised ratios (INRs) 2.0-2.9) +/- aspirin 75 mg daily, and (3) warfarin (INRs > 2.9) +/- aspirin 75 mg daily. Where patients had received two or three of these treatments successively, the periods of time on each treatment were added and the number of patients with recurrence(s) on each treatment were compared by Fisher's exact probability test. 'High' anticoagulation (INRs > 2.9) +/- aspirin 75 mg daily was more effective than aspirin 75 mg daily, there was a trend in favour of 'high' anticoagulation (P = 0.066). No statistically significant difference could be demonstrated when comparing 'low' anticoagulation +/- aspirin 75 mg daily with aspirin 75 mg daily (P = 0.092). These results suggest that aggressive anticoagulation with or without low-dose aspirin is effective in preventing further thromboembolic events in APS.