Levels in Plasma of the Serine Proteases and Associated Proteins of the Lectin Pathway Are Altered in Patients with Systemic Lupus Erythematosus

Objective. To examine whether proteins of the lectin pathway of the complement system are involved in systemic lupus erythematosus (SLE) pathogenesis. Methods. Using time-resolved immunofluorometric assays, plasma levels of mannan-binding lectin (MBL)-associated serine proteases 1 (MASP-1), MASP-2, MASP-3, MBL-associated protein of 19 kDa (MAp19), and MAp44 were determined in 58 patients with SLE and 65 healthy controls (HC). Results. Plasma concentrations in patients with SLE were higher than HC regarding MASP-1, MASP-3, and MAp44 (p < 0.0001, 0.0003, and 0.0013). Complement factor 3 correlated negatively and anti-dsDNA positively with levels of MAp19 (p = 0.0035, p = 0.0133). Conclusion. In SLE, plasma levels of MASP and MAp are altered and associated with SLE characteristics, supporting a role in SLE pathogenesis.