Objective: To measure the serum levels of clusterin, an antiinflammatory protein, which binds and inactivates complement, in patients with systemic lupus erythematosus (SLE) to determine whether the levels correlate with disease.
Methods: The levels of serum clusterin were measured by ELISA in 80 patients with SLE (76 female, 4 male). Clinical and serological information was gathered on 115 visits. Overall disease activity scores were determined using the Systemic Lupus Activity Measure-Revised.
Results: Serum clusterin levels were significantly decreased in patients with SLE and correlated inversely with disease activity (p < 0.00001). Low clusterin levels were significantly associated with skin ulcers (p < 0.0001), loss of hair (p = 0.002), proteinuria (p = 0.018), low platelet count (p = 0.03), and arthritis (p < 0.0001). The clusterin levels did not correlate with either systemic complement consumption, as measured by C3 or C4, or with prednisone use.
Conclusion: A highly significant correlation was observed between low levels of serum clusterin and a number of SLE disease features. This deficiency of clusterin could directly or indirectly affect the disease process. Individuals lacking sufficient amounts of clusterin systemically likely have poor control of antibody mediated inflammation at sites of apoptosis where autoantigens are exposed.