Objective: To elucidate the role of anticardiolipin antibodies (aCL) in the pathogenesis of hemolytic anemia in patients with systemic lupus erythematosus (SLE).
Methods: Immunoglobulins (Ig) and cardiolipin reactivity were evaluated in red blood cell (RBC) eluates and in the sera of patients with SLE and controls by a solid phase enzyme linked immunosorbent assay.
Results: aCL were detected in sera of 2 patients with SLE with active hemolytic anemia. The RBC eluates of these patients contained Ig (mainly IgG) with significant cardiolipin reactivity. RBC eluates from healthy volunteers failed to demonstrate measurable amounts of Ig whereas Ig eluted from RBC of chronic lymphocytic leukemia patients with active hemolysis but no aCL did not react with cardiolipin. Furthermore, under treatment, one patient went into complete remission with resolution of the hemolysis, negative Coombs' tests and lower serum aCL. The other patient, however, continued to demonstrate both high sera aCL and positive Coombs' tests.
Conclusion: aCL may play a direct role in the pathogenesis of hemolytic anemia in some patients with SLE by acting as anti-RBC autoantibodies.